The average amount customers at a certain grocery store spend yearly is $813.71. Assume the variable is normally distributed. If the standard deviation is $71.37, find the probability that a randomly selected customer spends between $638.85 and $942.18.
A) -0.029 = -2.9%
B) 1.080 = 108.0%
C) -0.041 = -4.1%
D) 0.957 = 95.7%

Question

Quizplus · Accepted Answer

The Z-scores for $638.85 and $942.18 are -2.45 and 1.80, respectively. The probability of a Z-score between -2.45 and 1.80 is approximately 0.957 or 95.7%.

The Average Amount Customers at a Certain Grocery Store Spend