Question

The manager of the quality department for a tire manufacturing company wants to know the average tensile strength of rubber used in making a certain brand of radial tire. She knows the population standard deviation and uses a Z test to test the null hypothesis that the mean tensile strength is 800 pounds per square inch. The calculated Z test statistic is a positive value that leads to a p-value of .047 for the test. If the significance level is .05, the null hypothesis would be rejected. Assume that the population of pressure values is normally distributed.

a) true
b) false

Answer 1

a) true

Explanation:

Decision Rule

If;

P-value > significance level --- accept Null hypothesis

P-value < significance level --- reject Null hypothesis

Z score > Z(at 95% confidence interval) ---- reject Null hypothesis

Z score < Z(at 95% confidence interval) ------ accept Null hypothesis

For the case above, the p-value for the test is 0.047 which is less than the significance level 0.05

P-value < 0.05

Using the decision rule, we will reject the Null hypothesis which is the same as stated in the question, which means its true.

_Confirmed._