Author Question: An advertising firm conducts 3 different campaigns, each in 14 different cities, to promote a ... (Read 59 times)

luminitza · **on:** Jul 24, 2018

An advertising firm conducts 3 different campaigns, each in 14 different cities, to promote a certain product, and tracks the product sales attributable to each campaign in each city. Determine whether the study is observational or designed.

A) observational B) designed

Question 2

An educator wanted to look at the study habits of university students.

As part of the research, data was collected for three variables - the amount of time (in hours per week) spent studying, the amount of time (in hours per week) spent playing video games and the GPA - for a sample of 20 male university students. As part of the research, a 95 confidence interval for the average GPA of all male university students was calculated to be: (2.95, 3.10). Which of the following statements is true?
A) In construction of the confidence interval, a t-value with 19 degrees of freedom was used.
B) In construction of the confidence interval, a t-value with 20 degrees of freedom was used.
C) In construction of the confidence interval, a z-value with 20 degrees of freedom was used.
D) In construction of the confidence interval, a z-value was used.