Question

HT Mean: A Packaging Company produces boxes out of cardboard and has a specified weight of 35 oz. It is known that the weight of a box is normally distributed with standard deviation 1.3 oz. A random sample of 36 boxes yielded a sample mean of 35.5 oz. At 5% level of significance, test the claim that the mean weight of a box is 35 oz or is there significant evidence that the mean weight is greater than 35 oz. Calculate the test statistic

Answer 1

Solution :

Given that

The null and alternative hypothesis is ,

= 35

= 35.5

= 1.3

n = 36

This will be a right tailed test because the alternative hypothesis is

This is the rigth tailed test .

The null and alternative hypothesis is ,

H0 :   = 35

Ha : > 35

Test statistic = z

= ( - ) / / n

= ( 35.5 - 35 ) / 1.3 / 36

= 2.31

The test statistic = 2.31