SOLUTION: The wait time for a company before a customer can talk to a customer service representative has a mean of 140 seconds with a standard deviation of 20 seconds. Suppose the distribut

Algebra ->  Probability-and-statistics -> SOLUTION: The wait time for a company before a customer can talk to a customer service representative has a mean of 140 seconds with a standard deviation of 20 seconds. Suppose the distribut      Log On


   

Question 929393: The wait time for a company before a customer can talk to a customer service representative has a mean of 140 seconds with a standard deviation of 20 seconds. Suppose the distribution of wait times is approximately bell-shaped and symmetric.

What is the approximate proportion of customers who wait time is under 100 seconds?

A 16%
B 32%
C 5%
D 2.5%
E 97.5%
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
mean = 140 seconds, SD = 20 seconds, z+=+blue%28x+-+140%29%2Fblue%2820%29
p(x < 100) = p(z < -40/20) = normalcdf(-100, -2) = .0228 = 2.28%
D the closest