A researcher estimates the 90% CI for a sample with a mean of M = 8.9 and a standard error ( )of 2.1.What is the confidence interval at this level of confidence?
A)90% CI 4.8,13.0
B)90% CI 5.5,12.4
C)90% CI 6.8,11.0
D)There is not enough information to answer this question.

Question

A researcher estimates the 90% CI for a sample with a mean of M = 8.9 and a standard error (  )of 2.1.What is the confidence interval at this level of confidence?
A)90% CI 4.8,13.0 
B)90% CI 5.5,12.4 
C)90% CI 6.8,11.0 
D)There is not enough information to answer this question.

Quizplus · Accepted Answer

The formula for calculating 90% confidence interval is:
CI = M ± (1.645)(SE)
CI = 8.9 ± (1.645)(2.1) = 5.5, 12.4
Therefore, the answer is B) 90% CI 5.5,12.4.

A Researcher Estimates the 90% CI for a Sample with a Mean