Question

nationwide, the average waiting time until a electric utility customer service representative answers a call is 360 seconds. The gigantic kilowatt energy company randomly sampled 40 calls and found that, on average, they were answered in 331 seconds with a population standard deviation of 30 seconds. can the company claim that they are faster than the average utility at a=0.05?

a. no because the test value -0.97 falls in the critical region

b. no because the test value is -0.15 falls in the critical region

c. yes because the test value -6.11 falls in the critical region

d. yes because the test value is -0.15 falls in the critical region.

Answer 1

Test statistic

z = -6.11

Critical value = -1.645

Hence,

We reject Ho because the test value -6.11 falls in the critical region.

Option C is correct.