Question

A producer of various kinds of batteries has been producing "D" size batteries with a life expectancy of 87 hours. Due to an improved production process, management believes that there has been an increasein the life expectancy of their "D" size batteries. A sample of 36 batteries showed an average life of 88.5 hours. It is known that the standard deviation of the population is 9 hours.

b.	Compute the test statistic.

Answer 1

solution:

this is the right tailed test .  

The null and alternative hypothesis is ,

H0 :   = 87

Ha : > 87

Test statistic = z

= ( - ) / / n

= (88.5-87) / 9/ 36

= 1