Question

QUESTION 25

1. I am doing a project on the average number of times per month college students eat out. I find a sample mean of 12.4 times. My margin of error, using 95% confidence, turns out to be 3.5 times. Which sentence below is the appropriate conclusion?

   	A.	I am 95% confident that the average college student eats out more than 12 times per month.
   	B.	I am 95% confident that between 8.9% and 15.9% of college students eat out at least once per month.
   	C.	I am 95% confident that the true percentage of all college students who like eating out is between 8.9% and 15.9%.
   	D.	I am 95% confident that the average number of times a college student eats out per month is between 8.9 times and 15.9 times.

   QUESTION 26

2. I am doing a project on the percentage of customers at my store who pay with credit card. I get a point estimate of 74.4% and a margin of error of 4.7%. If I used 90% confidence, what is the appropriate conclusion?

   	A.	I am 90% confident that Americans use a credit card for between 69.7% and 79.1% of all their purchases.
   	B.	I am 90% confident that the next customer who comes through my line will pay with credit card.
   	C.	I am 90% confident that the true percentage of all customers who pay with credit card at my store is between 69.7% and 79.1%.
   	D.	I am 90% confident that the average number of times a customer uses his credit card each month is between 69.7 and 79.1 times per month.

   QUESTION 27

3. Why is a margin of error needed in estimating parameters?

   	A.	Because we are just using a sample of the population to collect data from, the answer we get is only an estimate of the population.
   	B.	To allow for the possibility of calculation error when working with large data sets.
   	C.	To allow for the fact that people may not provide accurate information when asked the research question.
   	D.	To help account for bias that comes from the type of sample method used (like voluntary response or convenience sampling method).

Answer 1

Question 25

The confidence interval makes the estimate for whole population ( 12.4 - 3.5 , 12.4 + 3.5 ) = ( 8.9, 15.9 )

C) I am 95% confident that the true percentage of all college students who like eating out is between 8.9% and 15.9%.

Question 26

The confidence interval makes the estimate for whole population ( 74.4 - 4.7, 74.4 + 4.7 ) = (69.7, 79.1 )

C) I am 90% confident that the true percentage of all customers who pay with credit card at my store is between 69.7% and 79.1%.

Question 27

A) Because we are just using a sample of the population to collect data from, the answer we get is only an estimate of the population.

hence we need a margin in which the true value lies