A firm is studying the delivery times of two raw material suppliers. The firm is basically satisfied with supplier A and is prepared to stay with that supplier. However, if the firm finds that the mean delivery time of supplier B is less than that of supplier A, it will begin making raw material purchases from supplier B. Assume that 50 independent samples from each supplier show the delivery time of supplier A to be 14 days with a standard deviation of 3 days, while the delivery time of B is shown to be 12.5 days with a standard deviation of 2 days. Testing at a 0.05 level of significance, should the firm switch to supplier B or not?
Step 1: State the null and alternative hypothesis in words.
Step 2: Level of Significance and Critical Value/s and Region
Step 3: Compute test statistic
Step 4: Decision is __________
Step 5: State the conclusion