The manager of a computer help desk operation in Moncton has collected enough data to conclude that the time per call is normally distributed with a mean equal to 8.21 minutes and a standard deviation of 2.14 minutes. Based on this, what is the probability that a call will last longer than 13 minutes?
A) 0.0125
B) 0.4875
C) 0.5125
D) 0.9875
E) .0224

Question

Quizplus · Accepted Answer

To find the probability that a call will last longer than 13 minutes, we use the Z-score formula: Z = (X - μ) / σ, where X is the value in question (13 minutes), μ is the mean (8.21 minutes), and σ is the standard deviation (2.14 minutes). Plugging in the values, we get Z = (13 - 8.21) / 2.14 = 2.24. Looking up 2.24 in the Z-table gives us the probability of a call being less than 13 minutes. To find the probability of a call lasting longer than 13 minutes, we subtract this value from 1. The Z-table value for 2.24 is approximately 0.9875, so the probability of a call lasting longer than 13 minutes is 1 - 0.9875 = 0.0125.

The Manager of a Computer Help Desk Operation in Moncton