Question

According to CTIA-The Wireless Association, the mean monthly cell phone bill in 2018 was $60.64. A market researcher believes that the mean monthly cell phone bill has increased today.

a) What would be the null and alternative hypothesis for testing whether the mean monthly cell phone bill today has increased since 2018?

b) Calculate the P-Value if the researcher phones a random sample of 40 cell phone subscribers and gets a sample average of $67.45 with a sample standard deviation of $18.39.

c) What conclusion would you make using an alpha level of .05? (State your conclusion in terms of the problem)

Answer 1

Solution :

This is right tailed test .

The null and alternative hypothesis is ,

H0 :   = 60.64

Ha : > 60.64

Test statistic (t) =

= ( - ) / S / n

= (67.45 - 60.64) / 18.39 / 40

Test statistic = 2.34

P-value = 0.0122

= 0.05

P-value <

Reject the null hypothesis .

There is sufficient evidence to support the claim that the mean monthly cell phone bill has increased today