Question

Two researchers conducted a study in which two groups of students were asked to answer 42 trivia questions from a board game. The students in group 1 were asked to spend 5 minutes thinking about what it would mean to be a​ professor, while the students in group 2 were asked to think about soccer hooligans. These pretest thoughts are a form of priming. The 200 students in group 1 had a mean score of 24.1 with a standard deviation of 3.8 while the 200 students in group 2 had a mean score of 18.2 with a standard deviation of 3.6

Complete parts ​(a) and ​(b) below.

​(a) Determine the 90​% confidence interval for the difference in​ scores,μ1−μ2.

Interpret the interval.

The lower bound is:

The upper bound is:

Interpret the interval. Choose the correct answer below.

A.The researchers are 90​%confident that the difference of the means is in the interval.

B.There is a 90​% probability that the difference of the means is in the interval.

C.The researchers are 90​% confident that the difference between randomly selected individuals will be in the interval.

D.There is a 90​% probability that the difference between randomly selected individuals will be in the interval.

​(b) What does this say about​ priming?

A.Since the90​%confidence interval does not contain​ zero, the results suggest that priming does have an effect on scores.

B.Since the 90​%confidence interval contains​ zero, the results suggest that priming does not have an effect on scores.

C.Since the 90​% confidence interval contains​ zero, the results suggest that priming does have an effect on scores.

D.Since the 90​% confidence interval does not contain​ zero, the results suggest that priming does not have an effect on scores.

Answer 1

(A) Using TI 84 calulator

press stat then tests then 2-SampTint

enter the data

x1 = 24.1, s1 = 3.8, n1= 200

x2 = 18.2, s2 = 3.6, n2 = 200

Pooled: No

c-level = 0.90

press calculate

we get

(5.29, 6.51)

(B) we have calculated a 90% confidence interval, so we can say that the researchers are 90​%confident that the difference of the means is in the interval.

option A

(C) Since the confidence interval does not include 0, this means that the riming does have an effect on scores.

option A