Chapter 13.4, Problem 36ES

• In Exercises 31 to 40, answer each question. Round z-scores to the nearest hundredth and then find the required A values using Table 13.10 on page 787.

Telephone Calls A telephone company has found that the lengths of its long distance telephone calls are normally distributed, with a mean of 225 s and a standard deviation of 55 s. What percent of its long distance calls are

a. longer than 34() s?

b. between 200 and 300 s?