The average amount parents spent per child on back-to-school items in August 201

Question

The average amount parents spent per child on back-to-school items in August 2012 was $632 with a standard deviation of $186. 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 (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 numerical answer cell below MUST reference Excel output cells in the School sheet. Question 7 Find the probability the amount spent on a randomly selected child is greater than $291 Question 8 Find the probability the amount spent on a randomly selected child is less than $484 or greater than or equal to $904 Question 9 Find the probability the amount spent on a randomly selected child is less than or equal to $667 Question 10 Find the probability the amount spent on a randomly selected child is greater than $233 and less than $827

Explanation / Answer

7) P(x > 291)

z = (291 - 632)/186

z = - 1.833

P (z < - 1.83) = 0.334

8)

P(x > 904)

z = (904 - 632)/186

z = 1.46

P (z > 1.46) = 0.07215

Also,

P(x < 484)

z = (484 - 632)/186

z = - 0.80

P (z < - 0.80) = 0.21186

Add these two

0.21186 + 0.07215 = 0.28401

9)

P(x < 667)

z = (667 - 632)/186

z = 0.19

P (z < 0.19) = 0.425

10) P(233 < X < 827)

z = (233 - 632)/186

z = - 2.15

z = (827 - 632)/186

z = 1.05

P( -2.15 < z < 1.05) = 0.84

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