Answer: c. z = 1.35; Reject the null hypothesis
Step-by-step explanation:
Let be the average life expectancy of its batteries.
As per given , we have
Null hypothesis :
Alternative hypothesis :
Since is right-tailed and population standard deviation is also known, so we perform right-tailed z-test.
Test statistic :
where, n= sample size
= sample mean
= Population mean
=population standard deviation
For , we have
Critical one-tailed test value for 0.10 significance level :
Decision : Since critical z value (1.28) < test statistic (1.35), so we reject the null hypothesis .
[When critical value is less than the test statistic value , we reject the null hypothesis .]