Question

Four research teams each used a different method to collect data on how

fast a new brand of paint dries. Assume that they all agree on the sample size
and the sample mean (in minutes). Use the confidence level; confidence
interval) pairs below to select the team that has the smallest sample
standard deviation.
O
A. Confidence Level: 99.7%; Confidence Interval: 42 to 48
B. Confidence Level: 95%; Confidence Interval: 40 to 50
O
C. Confidence Level: 95%; Confidence Interval: 35 to 55
D. Confidence Level: 68%; Confidence Interval: 44.5 to 45.5

Answer 1

Answer: D

Explanation:

Answer 2

Option D.

Explanation:

Recall that the wider the confidence interval, the greater the variability.

In other words, wider confidence interval will have bigger sample standard deviation.

For option A, the width is |48-42|=6

For option B, the width is |50-40|=10

For option C, the width is |55-35|=20

For option D, the width is |45.5-44.5|=1

Therefore the team in option D has the smallest sample standard deviation.

As for the confidence level, it is just telling us the extent to which we confidence that, the parameter is within the interval