A small flower shop takes orders by phone and then one of the staff florists is assigned to prepare the arrangement. The time it takes to process phone orders is normally
Distributed with a mean of 6 minutes and a standard deviation of 2.5 minutes. The time it
Takes for an arrangement to be completed is normally distributed with a mean of 35
Minutes and a standard deviation of 8.6 minutes. What is the standard deviation for the
Total time to process a phone order and complete the floral arrangement at this flower
Shop (assuming times are independent)?
A) 8.96 minutes
B) 41 minutes
C) 80.28 minutes2
D) 4.87 minutes
E) 12.43 minutes

Question

Quizplus · Accepted Answer

The total time is the sum of two independent normal random variables, so the variance of the total time is the sum of the variances of the two individual times. The standard deviation is the square root of the variance, so the standard deviation of the total time is the square root of the sum of the variances of the two individual times.Therefore, the standard deviation of the total time is:sqrt(2.5^2 + 8.6^2) = 8.96 minutesSo the correct answer is A.

A Small Flower Shop Takes Orders by Phone and Then