Example7 6 1 Estimating big and tall population. transformation formula: σ −µ = X Z. The mean and the variance are the two parameters required to describe such a distribution. Step 2: The diameter of 120 cm is one standard deviation below the mean. If (μ) = 0 and standard normal deviation is equal to 1, then distribution is said These values are obtained by measuring by a thermometer. For some laptops, the time between charging the laptop battery is normally distributed with a mean of 50 hours and a standard deviation of 15 hours. 3% of the distribution of data is less than z = 1. May 13, 2023 · Table 5. Here, you can see some of the normal distribution examples and solutions. 2: The Standard Normal Distribution is shared under a license and was authored, remixed, and/or curated by via that was edited to the style and standards of the LibreTexts platform. Enter an X to represent the random variable, followed by the mean and the standard deviation, all separated by commas. (It is!) The probability distribution appears to be bell-shaped. A normal distribution has mean µ=100 and standard deviation s=15 (for example, IQ). (It is!) The density curve looks like a standard normal curve, but the tails of the \(t\)-distribution are "heavier" than the tails of the normal distribution. Note that the function fz() has no value for which it is zero, i. Then we would estimate where \(z = 1. 89) = 90. 45 = 0. 1 Standard Normal Distribution. The average operating life of a particular brand for an electric light bulb is 1200 hours, with a standard variation of 200 hours. The mean of the normal distribution determines its location and the standard deviation determines its spread. 5. Since it is a continuous distribution, the total area under the curve is one. This is also known as the z distribution. An airline claims that 72% 72 % of all its flights to a certain region arrive on time. For example, a book editor might be interested in the number of words spelled incorrectly in a particular book. Recall, SD Observed Mean Z − = a. 4 = -1. Assuming the weights follow the normal Word problems with normal distribution: “Between”: Steps. The mean of the z-scores is zero and the standard deviation is one. Compute the sample proportion. A normal distribution is a bell-shaped distribution. Solution: Use the following data for the calculation of standard normal distribution. The standard normal distribution is centered at zero and the degree to which a given measurement deviates from the mean is given by the standard deviation. μ is the mean of the data. 96 and 2. Example 2: Suppose X ~ N (8, 1). x = 3, μ = 4 and σ = 2. A standard normal random variable is a normally distributed random variable with mean μ = 0 μ = 0 and standard deviation σ = 1 σ = 1. 2. μ μ is the mean. x is the normal random variable. 45. Nov 21, 2023 · Two factors determine the characteristics of the distribution; which are mean ( μ) and standard deviation ( σ). Example 1: Suppose X ~ N (5, 6). Contents Toggle Main Menu 1 Definition 2 Standard Normal Distribution 2. 74, which means your score of 80 was 0. 5? Consulting our table of z -scores shows us that 0. Height. , 1. Jun 1, 2024 · The normal distribution formula is based on two simple parameters— mean and standard deviation —that quantify the characteristics of a given dataset. 7 feet tall. The normal distribution formula in statistics is given by, f (x,μ,σ) = 1 σ√2πe−(x−μ)2 2σ2 f ( x, μ, σ) = 1 σ 2 π e − ( x − μ) 2 2 σ 2. where X is a normal random variable, μ is the mean of X, and σ is the standard deviation of X . The length of a human pregnancy is normally distributed with a mean of 272 days with a standard deviation of 9 days (Bhat & Kushtagi, 2006). b) Divide the standard deviation (σ in Step 1) by the square root of your sample (n in Step 1): 8 / √ 4 = 4. x − M = 1380 − 1150 = 230. Example: Standard deviation in a normal distribution You administer a memory recall test to a group of students. 83 inches and a standard deviation of 2. The standard normal distribution is a special normal distribution. Normal Distribution (µ, s2) Jan 7, 2024 · The z-score. y Theorem f What is the Probability density function of the normal distribution? The normal distribution is described by two parameters: the mean, μ, and the standard deviation, σ. Most people recognize its familiar bell-shaped curve in statistical reports. Characteristics of the Normal distribution • Symmetric, bell shaped Learn how to solve any Normal Probability Distribution problem. For those of you who know calculus, if p of x is our probability density function -- doesn't have to be a normal distribution although it often is a normal distribution -- the way you actually figure out the probability, let's say between 4 and a half and 5 and half. The normal distribution is often described in terms of its variance σ2. a) P (X < 40) b) P (X > 21) c) P (30 < X < 35) A radar unit is used to measure the speeds of cars on a motorway. The table includes only positive values . This page titled 5. Mar 18, 2017 · By using the z-score formula: z = ( x - μ) / σ we can convert any distribution to the standard normal distribution. The amount of time spouses shop for anniversary cards can be modeled by an exponential distribution with the average amount of time equal to eight minutes. It has the following properties: Symmetrical. For example, suppose we have a set of data that follows the normal distribution with mean 400 and standard deviation 100. 6. 1 Finding areas under the standard normal curve. The battery usage time installed in a particular smartphone has a Normal distribution with a mean of 25. The distribution plot below is a standard normal distribution . Bell-shaped. The general form of its probability density function is The parameter is the mean or expectation of the distribution (and also its median and mode ), while the parameter is the Oct 23, 2020 · What is a normal distribution and how to use it in statistics? Learn the definition, formulas, examples, and applications of this common data pattern. 5 hours. c) Divide your result from a by your result from b: 13 / 4 = 3. Give limits, symmetric about the mean, within which 95% of the population would lie: Solution: This exercise is asking you to work with the following characteristic of the Normal distribution: If 2X 1, X 2, …. A. Solution: The formula for z-score that we have been using: Where −. Mar 26, 2023 · This page titled 5. z is called the standard normal variate and represents a normal distribution with mean 0 and SD 1. The z -score allows us to compare data that are scaled differently. “between $5,000 and Part 5: Normal Distribution | Free Worksheet and Solutions. 0. The Standard Normal has a random variable called Z. 0 and Aug 28, 2020 · Revised on June 21, 2023. Jun 16, 2023 · If x equals the mean, then x has a z -score of zero. Theoretically, a normal distribution is continuous and may be depicted as a density curve, such as the one below. Oct 2, 2020 · 00:25:20 – Overview of the Lognormal Distribution and formulas. Standard deviation = 2. There is nothing inherently wrong with non-normal data; some traits simply do not follow a bell curve. Most of the people in a specific population are of average height. 15m, so: 0. In probability theory and statistics, a normal distribution or Gaussian distribution is a type of continuous probability distribution for a real-valued random variable. Chapter Tests with Video Solutions. Find the probabilities. When graphing the data from each of the examples in the introduction, the distributions from each of these situations would be mound-shaped and mostly symmetric. Below are some normal distribution examples that will help further clarify this topic. 3. 9 years and 13. The command is called ‘normalpdf (’, and it is found by pressing [2nd] [DISTR] [1]. A z-score is a standardized value. 5 % = 16 %. X: the numbers associated with “between” (i. If X is a random variable that follows a normal distribution then it is denoted as \(X\sim N(\mu,\sigma ^{2})\). The Poisson probability distribution gives the probability of a number of events occurring in a fixed interval of time or space if these events happen with a known average rate and independently of the time since the last event. This question is really about is calculating standard normal scores. The calculation is as follows: x = μ + (z)(σ) = 5 + (3)(2) = 11. Que 1: Calculate the probability density function of normal distribution using the following data. 2E: The Standard Normal Distribution (Exercises) is shared under a CC BY 4. The solution is to convert the distribution we have with its mean and standard deviation to this new Standard Normal Distribution. 1 5. Example 1 1. The letter Z is used exclusively to denote a variable that has a standard normal distribution and is written Z ~ N(0, 1). 1 Definition 3 Converting Normal to Standard Normal 4 Normal Approximation to the Binomial Distribution 4. z = x − m σ (1) (1) z = x − m σ. 1. So, the calculation of Z-score can be done as follows-. Scribbr offers clear and concise explanations, diagrams, and calculators to help you master this topic. 8/11. An NBA player whose height is 85 inches is taller than average. Think about this transformation as of a ruler: for example, if you know your height in inches, you can use a formula to convert it into standard normal distribution. In this article, we go through the definition of normal distribution, their key parameters, the z-score and empirical rule and provide examples, concept-check questions and solutions. Jan 8, 2024 · The Standard Deviation Rule for Normal Random Variables. The data follows a normal distribution with a mean score of 50 and a standard deviation of 10. The height of people is an example of normal distribution. The t -distribution, also known as Student’s t -distribution, is a way of describing data that follow a bell curve when plotted on a graph, with the greatest number of observations close to the mean and fewer observations in the tails. I want to set up a specialty shop for men who are at least 6’ tall, but no more than 7' tall. 1 fz()= 1 2π e− 1 2 z2. X n 4 days ago · Normal Distribution Examples and Solutions. This bell-shaped curve is used in almost all disciplines. 5 lbs. We write X - N(μ, σ 2). Jul 1, 2020 · In the United States the ages 13 to 55+ of smartphone users approximately follow a normal distribution with approximate mean and standard deviation of 36. For a recent final exam in STAT 500, the mean was 68. Another example of a continuous random variable is the height of a randomly selected high school student. A log-normal distribution can be formed from a normal distribution using logarithmic mathematics. The z-score is three. 5. 0 and Suppose the heights of adult females is normally distributed with a mean of 66 inches and a standard deviation of 1. 3: The Standard Normal Distribution is shared under a CC BY 4. Mean = 4 and. 53. z = 1. Several genetic and environmental factors Problems with Solutions. 00:31:43 – Suppose a Lognormal distribution, find the probability (Examples #4-5) 00:45:24 – For a lognormal distribution find the mean, variance, and conditional probability (Examples #6-7) Practice Problems with Step-by-Step Solutions. Compute the following probability: Solution. This page titled 6. The number of people taller and shorter than the average height people is almost equal, and a very small number of people are either extremely tall or extremely short. with the mean of 0 and the standard deviation of 1. 48\) would be to the right of the mean at 0. For the standard normal distribution, 68% of the observations lie within 1 standard Exam Questions - Normal distribution, finding a probability - ExamSolutions. Apr 20, 2021 · The normal distribution is the most commonly used probability distribution in statistics. x = 1380. 1 produces the distribution Z ∼ N(0, 1). 7 years old. State the random variable. Where, x x is the variable. The word problem will identify: The mean (average or μ). Certain types of probability distributions are used in hypothesis testing, including the standard normal distribution, the F distribution, and Student’s t distribution. The extremely complicated probability distribution function for the Normal Distribution is: f(x) = 1 σ 2π−−√ e−1 2(x−μ σ)2, − To find the z-score for a particular observation we apply the following formula: Let's take a look at the idea of a z-score within context. Again, we distinguish between the variable, Z (capital Z), and its. You may assume that the normal distribution applies. If you scored an 80%: Z = ( 80 − 68. will take on a value between 0 and . Apr 2, 2023 · x = μ + (z)(σ) = 5 + (3)(2) = 11. 4: Areas of Tails of Distributions is shared under a CC BY-NC-SA 3. The z -score is three. 1. The graph below shows examples of Poisson distributions with normal distribution model. A standard normal distribution has a mean of 0 and standard deviation of 1. It will always be denoted by the letter Z Z. Shade below that point. 0 license and was authored, remixed, and/or curated by OpenStax via source content that was edited to the style and standards of the LibreTexts platform. 1 7. 55) 15. 1: The Normal Distribution is shared under a license and was authored, remixed, and/or curated by LibreTexts. Standard and general normal distributions De nition (Standard normal distribution) A continuous random ariablev is a standard normal (written N(0;1)) if it has density f Z(x) = 1 p 2ˇ e x2=2: A synonym for normal is Gaussian. A probability distribution of outcomes which is symmetrical or forms a bell curve is called a normal distribution. The normal distribution, which is continuous, is the most important of all the probability distributions. X is a normally distributed variable with mean μ = 30 and standard deviation σ = 4. And doing that is called "Standardizing": We can take any Normal Distribution and convert it to The Standard Normal Distribution. What is the probability that a car can be assembled in a period of time greater than 21 hours? Solution: For example, if the mean of a normal distribution is five and the standard deviation is two, the value 11 is three standard deviations above (or to the right of) the mean. 7% of scores are within 3 standard deviations of the mean. Since this is a standard normal problem we draw a standard normal Apr 9, 2022 · The Normal Distribution is symmetric and defined by two parameters: the expected value (mean) μ which describes the center of the distribution and the standard deviation σ, which describes the spread. 1 years, larger than the sample standard deviation of 2. Step 1: Subtract the mean from the x value. A normal distribution is a type of continuous probability distribution. original seven observations. 45m / 0. a flatter or steeper “dome” than a typical bell. 8, Then divide by the Standard Deviation: -12. Standard deviation (σ). Z = 1. Even when the phenomena in a sample distribution are not described well by the normal distribution, the sampling distribution of sample averages obtained by repeated sampling from the parent distribution is often described well by the normal distribution (Central limit theory). X ∼ Exp(0. 0 license and was authored, remixed, and/or curated by Anonymous via source content that was edited to the style and standards of the LibreTexts May 3, 2023 · Normal distribution: Solved Examples. the z-distribution). It is given by the formula 0. Jan 30, 2019 · We use our z -score formula to convert 73 to a standardized score. Common probability distributions include the binomial distribution, Poisson distribution, and uniform distribution. Here the Greek letter μ the mean and σ is the standard deviation. All other distributions with different : and σ can be converted into a standardized normal distribution using the . The Poisson distribution has only one parameter, λ (lambda), which is the mean number of events. If X is a normal random variable with general mean μ (not necessarily 0) and standard deviation σ (not necessarily 1), then it can be converted to standard normal by way of. 2: The Standard Normal Distribution is shared under a CC BY license and was authored, remixed, and/or curated by LibreTexts. So 26 is -1. 25. M = 1150. 67 inches, which is over 7. This means 68% of the data would fall between the values of 300 (one standard deviation below Jun 2, 2024 · Exercise 5. The graph above shows the standard normal distribution (with the mean 0). There are very few NBA players this tall so the answer is no, not likely. In this way, the t -distribution is more conservative than the standard normal distribution: to reach the same level of confidence or statistical significance , you will need to include a 3 days ago · The normal probability distribution formula is given as: P(x) = 1 2πσ2− −−−√ e−(x−μ)2 2σ2. 12 Standard Deviation from the Mean. 2 inches. For math, science, nutrition, history, geography, engineering, mathematics, linguistics, sports, finance, music…. Step 3: Add the percentages in the shaded area: 0. What is the probability of usage time greater than 32? The mass 3 The mass of certain types of cabbage is normally distributed with a mean of 1000 g and a standard deviation of 0. A particular value of Z is denoted z (lower-case) and is referred to as a z May 13, 2022 · A Poisson distribution is a discrete probability distribution. Sep 26, 2021 · Example 7. Since the mean for the standard normal distribution is zero and the standard deviation is one, then the transformation in Equation 6. For example, the probability that a standard normal is between 0 and 2 is 0. Step 1: Identify the parts of the word problem. What is the likelihood of a bulb surviving longer than 1150 hours? For example, if the mean of a normal distribution is five and the standard deviation is two, the value 11 is three standard deviations above (or to the right of) the mean. The standardized normal distribution is a type of normal distribution, with a mean of 0 and standard deviation of 1. Mean and median are equal; both located at the center of the distribution. Suppose that the heights of adult males is normally distributed with a mean of 70 inches and a standard deviation of 2. 7 years for the original seven observations. You can check this tool by using the standard normal distribution calculator as well. If a dataset is perfectly normally distributed, then 68% of the data values will fall within one standard deviation of the mean. Sep 17, 2020 · Around 99. The value of this random variable can be 5'2", 6'1", or 5'8". Find the probability of a pregnancy lasting less than 250 days. Example 1. The mean for the standard normal distribution is zero, and the standard deviation is one. Standard Score (aka, z-score) The normal random variable of a standard normal distribution is called a standard score or a z-score. To convert 26: First subtract the mean: 26-38. The normal distribution is a continuous probability distribution that is symmetrical around its mean, most Probability Distribution of a Normal Distribution. These are effectively the most likely outcome and how likely it is for a result to Nov 21, 2023 · Now, let us consider an example where a normal distribution is given and the mean weight of a girl is given: 80 lbs with a standard deviation of 2. Jan 3, 2023 · The t-distribution gives more probability to observations in the tails of the distribution than the standard normal distribution (a. 12. Use the z -score formula. For this problem, we would draw the standard normal curve and label 0 on the \(x\)-axis at the peak. σ is the standard deviation of data. 4. Aug 12, 2022 · To create a normal distribution, we will draw an idealized curve using something called a density function. The graph of the function is shown opposite. The notation for this is Z N(0, 1). For instance, about 34% of all data values lie between z z =0 (mean) and z z =1. For example, data about coffee and alcohol consumption are rarely bell shaped. 5424. The sample standard deviation of the 14 observations is 3. e. PROBABILITY AND DISTRIBUTION STATISTICAL TECHNIQUES-2Mathematics-4 (MODULE-4)LECTURE CONTENT:Normal Distribution example problemsArea under standard normal c Apr 30, 2018 · The normal distribution, also known as the Gaussian distribution, is the most important probability distribution in statistics for independent, random variables. Answer. Find the probability of a pregnancy lasting more than 280 days. 1 Worked Example 6 Worked Examples 1 7 Worked Example 8 Video Examples 9 Workbooks 10 External Resources 11 See Also Examples of Normal Distribution. Normal distribution 8. So to convert a value to a Standard Score ("z-score"): first subtract the mean, then divide by the Standard Deviation. The density function for a standard normal random variable is shown in Figure 7. 125); Jan 21, 2021 · Example \(\PageIndex{1}\) general normal distribution. Following the empirical rule: Around 68% of scores are between 40 and 60. Height = 79 + 3. Have a question about using Wolfram|Alpha? Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. In a random sample of 30 30 recent arrivals, 19 19 were on time. It be given by this area. z. Each decimal number in the table represents the probability (percentage) that a data value is between 0 and the corresponding z z -value. . 35 % + 13. Jan 21, 2022 · Definition: standard normal random variable. A z-score indicates the number of standard deviation a score falls above or below the mean. We began to get a feel for normal distributions in the Exploratory Data Analysis (EDA) section, when we introduced the Standard Deviation Rule (or the 68-95-99. The height 85 inches is 1. 74 SD above the mean Jun 30, 2024 · A standard normal distribution has the following properties: Mean value is equal to 0; Standard deviation is equal to 1; Total area under the curve is equal to 1; and; Every value of variable x is converted into the corresponding z-score. Jan 14, 2023 · 9. Find the z-score of x. SD = 150. 58) and their relationship to the normal distribution. In order to be considered a normal distribution, a data set (when graphed) must follow a bell-shaped symmetrical curve centered around the mean. A standard normal random variable \ (Z\) is a normally distributed random variable with mean \ (\mu =0\) and standard deviation \ (\sigma =1\). 05 inches. First verify that the sample is sufficiently large to use the normal distribution. It is a type of normal distribution used for smaller sample sizes, where the Normal Distribution - Explained Simply (part 1) This video describes the standard normal distribution and its properties with respect to the percentage of observations within each standard deviation. In the above normal probability distribution formula. All this formula is asking you to do is: a) Subtract the mean (μ in Step 1) from the greater than value (Xbar in Step 1): 25 – 12 = 13. 75 inches. The boy who is 170 cm tall is above average by 3 8 the remaining 90% of the standard normal distribution. A discrete probability distribution function has two characteristics: Jul 24, 2016 · The standard normal distribution is a normal distribution with a mean of zero and standard deviation of 1. The standard normal distribution has a mean of 0 and a standard deviation and variance of 1. If you input the mean this is why the normal distribution is sometimes called the Gaussian distribution. k. Write the distribution, state the probability density function, and graph the distribution. The number of standard deviations from the mean is called the z-score and can be found by the formula. Normal distribution The normal distribution is the most widely known and used of all distributions. 2. Step 2: Divide the difference by the standard deviation. z = 230 ÷ 150 = 1. Consider the mean given to you, like 850, with a standard deviation of 100. Suppose x= 17. 15m = 3 standard deviations. Normal Distribution: P (more than x) where x is less than the mean In this tutorial we show you how to calculate the probability given that x is less than the mean from a normal distribution by looking at the following example. 9 years, respectively. By the formula of the probability density of normal distribution, we can write; Mar 15, 2024 · Example #1. Let be a normal random variable with mean and variance . The following diagram shows the formula for Normal Distribution. It represents a distribution of standardized scores, called z-scores, as opposed to raw scores (the actual data values). 4772. 2 hours and a standard deviation of 7. So if Z is a standard normal variable, μZ = 0, σZ = 1, σ2. Mar 12, 2023 · 6. “choose one at random” or “select ten at random”). Jun 9, 2022 · Heads. Its graph is bell-shaped. 8 = -12. The probability distribution appears to be symmetric about \(t=0\). Example 1: Let us consider the Gaussian distribution example: The time taken to assemble a car in a certain plant is a random variable having a normal distribution of 30 hours and a standard deviation of 4 hours. Its distribution is the standard normal, Z∼N (0,1). • What is the z value for the 10’th percentile of the standard normal distribution • Find “a” such that Pr{z < a} = 0. It also makes reference to two key statistical demarcation points (i. a. So the question becomes: what is the area under the standard normal distribution for z greater than 1. I. First of all, we need to express the above probability in terms of the distribution function of : Then, we need to express the distribution function of in terms of the distribution function of a standard normal random variable : Mar 27, 2023 · The value of \(Z\) that cuts off a right tail of area \(c\) in the standard normal distribution is denoted \(z_c\). Using the standard normal table, typically called the normal table, to find the probability of one standard deviation, go to the Z column, reading down to 1. Find the z-score corresponding to a raw score of 132 from a normal distribution with mean 100 and standard deviation 15. Solution 1: Given variable x = 3. Sep 16, 2022 · The z -score tells you how many standard deviations away 1380 is from the mean. The value x comes from a normal distribution with mean μ and standard deviation σ. The rst thing to do is to show that this is a (probability) densit. 5424 standard deviations above the mean. To get areas for more general intervals, use the symmetry property, and the fact that the total area under φ 1. Because the normal distribution approximates many natural phenomena so well, it has developed into a standard of reference for many probability problems. Solution: First, the mean of this normal distribution is = 1200 and the standard deviation is ˙= 300, so the z-score standardization formula is x ˙ = x 1200 300 The solutions of each part are itemized below (1)For the possible value x= 1200, we nd that x 1200 300 = 1200 1200 300 = 0 This might seem confusing, but the mean of standard normal 7. Solution: Step 1: Sketch a normal distribution with a mean of μ = 150 cm and a standard deviation of σ = 30 cm . While the mean indicates the “central The probability is given by the area under that curve. 0. This tutorial first explains the concept behind the normal distribution, then it discusses h Non-normal distributions may lack symmetry, may have extreme values, or may have. Tails. A normal distribution with mean μ = 0 and standard deviation σ = 1 is called the standard normal distribution. The speeds are normally distributed with a mean of 90 km/hr and a standard deviation of 10 km/hr. The continuous probability distribution of a random variable whose logarithm is normally distributed is called a lognormal distribution. Apr 2, 2023 · This page titled 6. Scroll down the page for more examples and solutions on using the normal Convert the values to z - scores and prepare the Normal Distribution Graph. Number selected (i. 15 kg. You are required to calculate a standard normal distribution for a score above 940. Find out how to calculate the mean, standard deviation, and z-scores of a normal distribution, and how to compare it with other distributions. Watch on. Every normal random variable X can be transformed into a z score via the following equation: z = ( X - μ) / σ. 7 rule) for how values in a normally-shaped sample data set behave relative to their sample mean (x-bar) and sample standard deviation (s). Clearly σ is found as the square root of σ2. The z -score for a value of 1380 is 1. Example: A carton of orange juice has a volume which is normally distributed with a mean of 120ml and a standard This is the probability that a standard normal random variable. This says that X is a normally distributed random variable with mean μ = 5 and standard deviation σ= 6. Here we calculate (73 – 70) / 2 = 1. 15 % + 2. 5(3. The standard deviation is 0. Determine the probability that a random smartphone user in the age range 13 to 55+ is between 23 and 64. 1: Tall Men in an Area. Those values are obtained by measuring by a ruler. Sep 27, 2022 · Solution: It is first helpful to draw the standard normal curve, label the mean, label the given \(z\)-value, and shade the area of the probability desired. A normal distribution is a perfectly …. Example 2 Suppose the chest sizes of 19th century Scottish Militiamen are normally distributed with a mean of 39. In the United States, the height of men follows a normal distribution with a mean of 70 inches (5' 10") and a standard deviation of 3 inches. 55 with a standard deviation of 15. ∼. 100 Normal Dist # 28 Solution Strategy 1) A) Draw a bell curve and drop a mean. It gives the probability of an event happening a certain number of times ( k) within a given interval of time or space. − μ. 1 Conditions 5 Reading the Tables 5. The parameters of the normal are the mean µ and the standard deviation σ. 933 = 93. It has a mean of 0 and its standard deviation is equal to 1. jd za ww ya oo jm si bs gy he