Estimating the Difference between Two Population Proportions — Unit test
Question 10 • CA-Statistics and Probability B
A major car dealership has several stores in a big city. The owner wants to determine if there is a difference in the proportions of SUVs that are sold at stores A and B. The owner gathers the sales records for each store from the past year. A random sample of 55 receipts from store A shows that 30 of the sales were for SUVs. Another random sample of 60 receipts from store B shows that 45 of the sales were for SUVs.Based on the 99% confidence interval, (–0.43, –0.02), is there convincing evidence of a difference in the proportions of sales that are SUVs for the two stores?
Answer
A
There is convincing evidence because the entire interval is below 0.
B
There is convincing evidence because the two sample proportions are different.
C
There is not convincing evidence because another confidence interval that uses a higher level of confidence might contain 0.
D
There is not convincing evidence because two different sample sizes were used. In order to determine a difference, the same number of sale records should be selected from each population.