Question

A local pizza place claims that they average a delivery time of 10.14 minutes. To test this claim, you order 13 pizzas over the next month at random times on random days of the week. You calculate that the average delivery time is 8.59 minutes with a standard deviation of 1.721 minutes. You create a 99% confidence interval of (7.13, 10.05). Of those listed below, what is the best conclusion you can make?

Question 7 options:

	1) The percentage of pizzas that arrive around 10.14 minutes is 99%.
	2) You are 99% confident that the average delivery time is greater than 10.14 minutes.
	3) The average delivery time does not significantly differ from 10.14 minutes.
	4) We cannot determine the proper interpretation based on the information given.
	5) You are 99% confident that the average delivery time is less than 10.14 minutes.

A pharmaceutical company is testing a new drug to increase memorization ability. It takes a sample of individuals and splits them randomly into two groups. One group is administered the drug, and the other is given a placebo. After the drug regimen is completed, all members of the study are given a test for memorization ability with higher scores representing a better ability to memorize. You are presented a 99% confidence interval for the difference in population mean scores (with drug - without drug) of (-26.54, -12.1). What can you conclude from this interval?

Question 8 options:

	1) We are 99% confident that the average memorization ability of those on the drug is higher than those who are not on the drug.
	2) We are 99% confident that the difference between the two sample means falls within the interval.
	3) There is no significant difference between the average memorization abilities for those on the drug compared to those not on the drug.
	4) We do not have enough information to make a conclusion.
	5) We are 99% confident that the average memorization ability of those not on the drug is higher than those who are on the drug.

Answer 1

Solution:

Question 7)

Given:  a 99% confidence interval: (7.13, 10.05).

Claim: A local pizza average a delivery time is 10.14 minutes.

Since both the limits of 99% confidence interval are less than claimed mean of 10.14 minutes, that means average delivery time is significantly less than 10.14 minutes.

Thus correct option is:
5) You are 99% confident that the average delivery time is less than 10.14 minutes.

Question 8)

Given: a 99% confidence interval for the difference in population mean scores (with drug - without drug) is: (-26.54, -12.1).

Here we have a 99% confidence interval is: (-26.54, -12.1) and differences of means are taken as With Drug - without Drug

Both the limits are negative means first variable has lower mean than second mean, that is with drug has less mean than that of without drug.

That is: Without drug has large means

that is: Without drug has  memorization ability with higher scores representing a better ability to memorize.

Thus correct option is:

5) We are 99% confident that the average memorization ability of those not on the drug is higher than those who are on the drug