Testing a Claim about a Difference between Means — Quiz
Question 3 • Statistics
A manufacturing company packages shipments in either large or small boxes. A random sample of 40 shipments that are packaged in large boxes is found to have a mean of 15 pounds and a standard deviation of 2 point 8 pounds. A separate random sample of 50 shipments that are packaged in small boxes is found to have a mean of 10 pounds and a standard deviation of 1 point 5 pounds. The manager would like to know if the data provide convincing evidence that the true mean weight of all shipments that are packaged in small boxes is less than the true mean weight of all shipments that are packaged in large boxes. The manager tests ratio of cap h sub 0 to mu sub cap s minus mu sub cap l is equal to 0 , ratio of cap h sub A to mu sub cap s minus mu sub cap l is less than 0 , where mu sub cap l is equal to the true mean weight of all shipments that are packaged in large boxes and mu sub cap s is equal to the true mean weight of all shipments that are packaged in small boxes. The conditions for inference have been met. The standardized test statistic is t is equal to negative 10 point 1 9 and the cap p -value is less than 0 point 0 0 0 5 What conclusion should be made using the significance level alpha is equal to 0 point 0 1 ?
Answer
A
Fail to reject cap h sub 0 . There is convincing evidence that the true mean weight of all shipments packaged in small boxes is less than the true mean weight of all shipments packaged in large boxes.
B
Fail to reject cap h sub 0 . There is not convincing evidence that the true mean weight of all shipments packaged in small boxes is less than the true mean weight of all shipments packaged in large boxes.
C
Reject cap h sub 0 . There is not convincing evidence that the true mean weight of all shipments packaged in small boxes is less than the true mean weight of all shipments packaged in large boxes.
D
Reject cap h sub 0 . There is convincing evidence that the true mean weight of all shipments packaged in small boxes is less than the true mean weight of all shipments packaged in large boxes.
Explanation
The p-value is less than 0.0005, which is smaller than the significance level of 0.01. Therefore, reject the null hypothesis that the two population means are equal. The data provide convincing evidence that the true mean weight of shipments packaged in small boxes is less than the true mean weight of shipments packaged in large boxes.
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