Answers must be in the FOURTH DECIMAL. 79 80 81 82 and information in Questions

Question

Answers must be in the FOURTH DECIMAL.

79 80 81 82 and information in Questions 7-13), generate excel output in the given space on the School sheet in this workbook to answer the following questions. Each orange 83 numerical answer cell below MUST reference Excel output cells in the School sheet. 84 85 86 87 The average amount parents spent per child on back-to-school items in August 2012 was $683 with a standard deviation of $266. Assume the amount spent on back-to- school items is normally distributed. Place this information in the School Sheet in this workbook and use it to answer the following questions. Based on this information Question 7 Find the probability the amount spent on a randomly selected child is greater than $321. 89 90 91 92 93 94 95 96 97 Question 8 Find the probability the amount spent on a randomly selected child is less than $587 or greater than or equal to $912. Question 9 Find the probability the amount spent on a randomly selected child is less than or equal to $729. 10 Find the probability the amount spent on a randomly selected child is greater than $225 and less than $756. 100 101 102 103 104 105 106 107 108 Question 128 Find the lower endpoint using Excel. Use this lower endpoint and some math to find the upper endpoint. (Remember the label) 109 Question 11 The probability is 0.98 that the amount spent on a randomly selected child is no less than what value? (Remember the label.) Question 12A The probability is 0.40 that the amount spent on a randomly selected child will be between what two values equidistant from the mean?

Explanation / Answer

Answer to the question as follows:

Mean = 683

Stdev = 266

7.P(X>321) = P(Z> (631-683) / 266) = P(Z>-.196) = 1-.4207 = .5793

8.P(X<587 or X>912) = P(Z< -.37<Z<.86) = .8051-.3557 = .45

9.P(X>729) = =P(Z>(729-683) / 266) = P(Z>.173) = 1-.5675 = .4325

10.P(Z>225 or X<756) = P(-1.72<Z<.27) = .608-.2744 = .334

11.P(X>=c) = .98, z for .98 is -2.06, c = 683+266*-2.06 = 135.04

12A: P(-c<=X<=c) = 2*P(-c<=X<=0) =.40,P(-c<X<0) = .20 , Z= -.525 ,

Lowerbound c = -.525*266+683 = 543.35 and upper bound = +.525*266+683 = 822.65

12B:Use the formula: =NORM.INV(0.3,683,266) and =NORM.INV(0.7,683,266) to get :543.35 and 822.65

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