# Question: A telephone company claims that the mean duration of all

A telephone company claims that the mean duration of all long-distance phone calls made by its residential customers is 10 minutes. A random sample of 100 long-distance calls made by its residential customers taken from the records of this company showed that the mean duration of calls for this sample is 9.20 minutes. The population standard deviation is known to be 3.80 minutes.

a. Find the p-value for the test that the mean duration of all long-distance calls made by residential customers of this company is different from 10 minutes. If α = .02, based on this p-value, would you reject the null hypothesis? Explain. What if α = .05?

b. Test the hypothesis of part a using the critical-value approach and α = .02. Does your conclusion change if α = .05?

a. Find the p-value for the test that the mean duration of all long-distance calls made by residential customers of this company is different from 10 minutes. If α = .02, based on this p-value, would you reject the null hypothesis? Explain. What if α = .05?

b. Test the hypothesis of part a using the critical-value approach and α = .02. Does your conclusion change if α = .05?

**View Solution:**## Answer to relevant Questions

Explain which of the following is a two-tailed test, a left-tailed test, or a right-tailed test. a. H0: µ = 45, H1: µ > 45 b. H0: µ = 23, H1: µ ≠ 23 c. H0: µ > 75, H1: µ < 75 Show the rejection and non-rejection ...A journalist claims that all adults in her city spend an average of 30 hours or more per month on general reading, such as newspapers, magazines, novels, and so forth. A recent sample of 25 adults from this city showed that ...A random sample of 14 observations taken from a population that is normally distributed produced a sample mean of 212.37 and a standard deviation of 16.35. Find the critical and observed values of t and the ranges for the ...The police that patrol a heavily traveled highway claim that the average driver exceeds the 65 miles per hour speed limit by more than 10 miles per hour. Seventy-two randomly selected cars were clocked by airplane radar. The ...According to an estimate, 2 years ago the average age of all CEOs of medium-sized companies in the United States was 58 years. Jennifer wants to check if this is still true. She took a random sample of 70 such CEOs and found ...Post your question