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

Multiple Choice

A researcher estimates the 90% CI for a sample with a mean of M = 8.9 and a standard error ( $\sigma$ _M) 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.