Question

A cell phone user wants to determine what data plan she should get on her new contract. She selects a random sample of 15 months and finds her average usage to be 11.25 GB with a standard deviation of 2.5 GB. She wants to test H₀: µ ≥ 12 GB versus H_a: µ < 12 GB. What is the value of the test statistic and the associated pvalue?

Answer 1

Solution :

= 12

= 11.25

s = 2.5

n = 15

This is the left tailed test .

The null and alternative hypothesis is ,

H₀ :   ≥ 12

H_a : < 12

Test statistic = t

= ( - ) / s / n

= (11.25-12) /2.5 / 15

= -1.162

P(z < -1.162 ) = 0.1324

P-value = 0.1324