6.4: Applications of the Standard Normal Distribution By the end of class you will be able to solve real world problems using the normal distribution and determine if a distribution is normal.
The average admission charge for amusement parks is normally distributed with a mean of $45 and standard deviation of $6.50. Find the probability that an amusement park ticket is less than $40. .2209
Method 1: Convert to z value Use the formula to convert variable to z value Use normalCDF (low, high, z)
Method 2: No Conversion Use normCDF (low, high, mean, st. dev)
The winnings of Wheel of Fortune contestants are normally distributed with a mean of $16,000 and a standard deviation of $2,100
Calculate the following P(X<$15,000) P(X>$19,000) P($9,000<X<$24,500) 1) .1169, 2) 0, 3) .0764
The average length of a hospital stay is 5. 9 days The average length of a hospital stay is 5.9 days. If we assume a normal distribution and a standard deviation of 1.7 days, 15% of hospital stays are less than how many days? 4.13
Finding Variable Values Use invNORM( area to left, mean, st. dev)
The average person is willing to spend $6,000 on a used car The average person is willing to spend $6,000 on a used car. He wants to sell cars that appeal to the middle 70% of the population. The distribution is normally distributed with a standard deviation of $500. Find the minimum and maximum prices of a car that the dealer will sell. 5481, 6518
The following data represents the number of runs scored by a baseball player each year of his career. Check for normailty. 30 59 69 50 58 71 55 43 66 52 56 62 36 13 29 17 3 Create a frequency table and histogram with students, mean = 45.24, median = 52, s = 20.58, Q1 29.5, Q3 60.5, PI (-.985), Quartile Check: IQR = 31, Q1-1.5(IQR) = -17, Q3+1.5(IQR) = 107
Tests for Normality Construct a frequency distribution and histogram (bell curve) Use Pearson’s Index: (s = standard deviation) Check for outliers using IQR (Q1—1.5IQR, Q3+1.5IQR)
A survey of grocery stores showed how many days’ inventory the stores had. Check for normality. 5 29 34 44 45 63 68 74 74 81 88 91 97 98 113 118 151 158 See book pg 313. Have different rows do different tests.