Question

Question 1

A) An ACME Bearings manager wants to compare the average ball bearing
sizes from two different machines. She suspects the mean diameter for
bearings from machine 2 exceeds that of bearings from machine 1. She
takes two independent, random samples of size 50, one from each
machine. The mean and standard deviation of bearings taken from
machine 1 are 3.302 mm and 0.051 mm. The mean and standard deviation
of bearings taken from machine 2 are 3.355 mm and 0.050 mm. Run a
hypothesis test consistent with her suspicions. Be sure to
a. check all necessary assumptions;
b. state the null and alternative hypotheses;
c. decide whether or not to pool and explain why;
d. calculate the test statistic and p-value;
e. state your conclusion in a complete sentence based on the p-value.

B) Use the data from the previous problem to make a 98% t-interval for the
difference between the true means. In doing so, be sure to
a. check all necessary assumptions for making the t-interval;
b. calculate the interval endpoints;
c. interpret the interval in a complete sentence.

Answer 1