Tata Motor supplies a rear axle for Postal service mail trucks. These axles must be able to

withstand 80000 pounds per square inch in stress tests, but an excessively strong axle raises

production costs significantly. Long experience indicates that the standard deviation of the

strength of its axles is 4000 pounds per square inch. The Manufacturer selects a sample of 100

axles from production, tests them, and finds that the mean stress capacity of the sample is

79600 pounds per square inch.

i. Formulate the null and alternate hypothesis

ii. If manufacturer uses a significance level of 0.05 in testing, will the axles meet his

stress requirements? (Take Z = 1.96)