Question

A company claims that the mean battery life of their MP3 player is = 30 hours. You suspect this claim is incorrect and find a random sample of 18 MP3 players has a mean battery life of 28.5 hours and a standard deviation of 7 hours. Is there enough evidence to reject the null hypothesis a=0.01?         Ho: u=30 Ha: not = 30.

Answer 1

Solution :

= 30

=28.5

S =7

n = 18

This is the two tailed test .

The null and alternative hypothesis is ,

H0 :    = 30

Ha :     30

Test statistic = t

= ( - ) / S / n

= (28.5 - 30) / 7 / 18  

= -0.909

Test statistic = t =-0.909  

P-value =0.3760

= 0.01

P-value >

0.3760 > 0.01

Fail to reject the null hypothesis .

There is insufficient evidence to suggest that