Ultimate SAT Study Guide - Questions & Answers

Suppose you are the manager of Speedy Oil Change which claims that it will change the oil in customers cars in less than 30 minutes on average. Further suppose that several complaints have been filed from customers stating that their oil change took longer than 30 minutes. Upper-level management at Speedy Oil Change headquarters has requested that you investigate the complaints. To begin your investigation, you randomly audit 36 oil changes performed by Speedy Oil Change and record the time each customer waited for the oil change. The number of minutes to complete each of the 36 oil changes is reported below. Suppose you are the manager of Speedy Oil Change which claims that it will change the oil in customers cars in less than 30 minutes on average. Further suppose that several complaints have been filed from customers stating that their oil change took longer than 30 minutes. Upper-level management at Speedy Oil Change headquarters has requested that you investigate the complaints. To begin your investigation, you randomly audit 36 oil changes performed by Speedy Oil Change and record the time each customer waited for the oil change. The number of minutes to complete each of the 36 oil changes is reported below. 42 29 19 11 10 27 41 27 22 26 28 32 17 15 25 35 32 22 13 31 17 30 33 25 18 24 28 21 40 19 3430 14 23 22 10 1. Write the null and alternative hypothesis. Label each accordingly. 2. Calculate the Test Statistic and the P-value. Label each accordingly, and report the P-value to 4 decimal places. 3. Using the P-value calculated in #2, explain why you would or would not reject the null hypothesis? Answer using a complete sentence, proper grammar and correct spelling. Do NOT write a conclusion. 4. Based on your answer to #3, write a final conclusion for the test of hypotheses, and explain if the company is fulfilling its promise to change the oil in customers cars in less than 30 minutes on average? Answer using a complete sentence, proper grammar and correct spelling.