( 4 decimal places) 2. Find the value of z if the area under a Standard Normal curve a) to the right of z is 0.3632; b) to the left of z is 0.1131; c) between 0 and z‚ with z > 0‚ is 0.4838; d) between -z and z‚ with z > 0‚ is 0.9500. Ans : a) z = + 0.35 ( find 0.5- 0.3632 = 0.1368 in the normal table) b) z = -1.21 ( find 0.5 – 0.1131 = 0.3869 in the normal table) c ) the area between 0 to z is 0.4838‚ z = 2.14 d) the area to
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Deviation Definition: Behavior commonly seen in children that is the result of some obstacle to normal development such behavior may be commonly understand as negative (a timid child‚ a destructive child) or positive (a quite child)‚ both positive and negative deviation will disappear once the child begins to concentrate on a piece of work freely chosen by him. The physical deforms are easier to identify. This can be by birth due to an accident etc… and most such physical deforms
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Standard Deviation (continued) L.O.: To find the mean and standard deviation from a frequency table. The formula for the standard deviation of a set of data is [pic] Recap question A sample of 60 matchboxes gave the following results for the variable x (the number of matches in a box): [pic]. Calculate the mean and standard deviation for x. Introductory example for finding the mean and standard deviation for a table: The table shows the number of children living
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values. σ = 3 0.95 σ = 1 0.95 X 19 25 31 -2 0 +2 Normal curve showing Standard normal curve showing area between 19 and 31 area between -2 and +2 Entry to a certain University is determined by a national test. The scores on this test are normally distributed with a mean of 500 and a standard deviation of 100. Tom wants to be admitted to this university and he knows that he must score better than at least 70% of the
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Normal Distribution It is important because of Central Limit Theorem (CTL)‚ the CTL said that Sum up a lot of i.i.d random variables the shape of the distribution will looks like Normal. Normal P.D.F Now we want to find c This integral has been proved that it cannot have close form solution. However‚ someone gives an idea that looks stupid but actually very brilliant by multiply two of them. reminds the function of circle which we can replace them to polar coordinate Thus Mean
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STANDARD DEVIATION The standard deviation is a popular measure of variability. It is used both as a separate entity and as a part of other analyses‚ such as computing confidence intervals and in hypothesis testing. The standard deviation is the square root of the variance. The population standard devia¬tion is denoted by σ. Like the variance‚ the standard deviation utilizes the sum of the squared deviations about the mean (SSx). It is computed by averaging these squared deviations (SSX/N) and
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of this sample? What is the standard deviation? The mean age is 47.5 years old. The standard deviation is 10.74832 years. http://www.calculator.net/standard-deviation-calculator.html Sample Standard Deviation‚ s: 10.748316881702 Sample Standard Variance‚ s2 115.52631578947 Total Numbers‚ N 20 Sum: 950 Mean (Average): 47.5 Population Standard Deviation‚ σ 10.476163419878 Population Standard Variance‚ σ2 109.75 If it follows the normal distribution The 68.3% measure confidence
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DESCRIPTIVE STATISTICS: NUMERICAL MEASURES MULTIPLE CHOICE QUESTIONS In the following multiple choice questions‚ circle the correct answer. 1. Which of the following provides a measure of central location for the data? a. standard deviation b. mean c. variance d. range Answer: b 2. A numerical value used as a summary measure for a sample‚ such as sample mean‚ is known as a a. population parameter b. sample parameter c. sample statistic
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The population standard deviation σ of a discrete random variable ‚ Measure how close a random variable tends to be the population mean μ‚ so you must understand μ before you understand σ If you have a random variable like a bet at a casino or and investment then the standard deviation σ measure the risk‚ if there is a lot of risk then the standard deviation is high The formulas for standard deviation are given below but you should look at the examples first Population mean Population variance
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Business Statistics MGSC-372 Review Normal Distribution The Normal Distribution aka The Gaussian Distribution The Normal Distribution y 1 f ( x) e 2 1 x 2 2 x Areas under the Normal Distribution curve -3 -2 - 68% 95% 99.7% + +2 +3 X = N( ‚ 2 ) Determining Normal Probabilities Since each pair of values for and represents a different distribution‚ there are an infinite number of possible normal distributions. The number of statistical tables
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