Question

Four research teams each used a different method to collect data on how fast a new strain of maize sprouts. Assume that they all agree on the sample size and the sample mean (in hours). Use the (confidence level; confidence interval) pairs below to select the team that has the smallest sample standard deviation.


A

. Confidence Level: 99.7%; Confidence Interval: 42 to 48  
B. Confidence Level: 95%; Confidence Interval: 43 to 47
  C. Confidence Level: 68%; Confidence Interval: 44 to 46  
D. Confidence Level: 95%; Confidence Interval: 44 to 46

Answer 1

Confidence Level: 95%; Confidence Interval: 44 to 46

Answer 2

D

Explanation:

First of all we know that confidence interval includes

Mean + or - z critical value (std deviation)

The larger the confidence level the longer the confidence interval would be.

Here given the confidence level for four research teams each used a different method to collect data on how fast a new strain of maize sprouts

.Confidence Level: 99.7%; Confidence Interval: 42 to 48

B.Confidence Level: 95%; Confidence Interval: 43 to 47

C.Confidence Level: 68%; Confidence Interval: 44 to 46

D.Confidence Level: 95%; Confidence Interval: 44 to 46

Comparing B and D we find that D is having less std deviation as length is narrower.

Comparing D with C, we conclude that for same 44 to 46 C used only 68%

So C must have had higher std dev than D

Similarly A and D comparison shows that A has more longer interval and more std deviation.

So answer is D which has the smallest std dev