At Netflix, the time it takes for a returned DVD to be re-filed and for the next DVD to be submitted for shipping to the customer follows a bell-shaped pattern, with a mean of 194 seconds and a standard deviation of 42 seconds.What proportion of the "turnaround" times are between 200 and 220 seconds?
A).1767
B).1986
C).2540
D).3121
E).2242

Question

Quizplus · Accepted Answer

The z-scores for 200 and 220 seconds are (200 - 194) / 42 = 1.43 and (220 - 194) / 42 = 2.86, respectively. The proportion of the "turnaround" times between 200 and 220 seconds is the area under the normal curve between these two z-scores, which is 0.1767.

At Netflix, the Time It Takes for a Returned DVD