Think of a vending machine on campus. The vending machine has a coin collector that should be emptied regularly. In the past, the vending machine company emptied the coin collector every 14 days, and recorded the weight of the coin collector when it is emptied. In the past 100 visits, the average weight of the coin collector was 22 pounds and the standard deviation was 8.
If the coin collector is full, the vending machine is unusable. But emptying the collector is also an expense. The company finds that it is optimal to empty a coin collector when it weighs 20 pounds. The company wants to test the following hypotheses:
Null hypothesis: the mean weight of the coin collector emptied every 14 days is 20 pounds.
Alternative hypothesis: the mean weight of the coin collector emptied every 14 days is not 20 pounds.
Find the t-statistic of the test, and determine if the null hypothesis is rejected at the significance level of 5%. (Round the t-statistic to the second decimal place.)
a. t-statistic is 2, so the null hypothesis is not rejected.
b. t-statistic is 1.25, so the null hypothesis is not rejected.
c. t-statistic is 2, so the null hypothesis is rejected.
d. t-statistic is 2.5, so the null hypothesis is not rejected
e. t-statistic is 1.25, so the null hypothesis is rejected.
f. t-statistic is 2.5, so the null hypothesis is rejected.