An analyst for a large national credit union wishes to estimate the mean checking account at the institution. He selected a random sample of 40 accounts and used the data to calculate the following 90% confidence interval for the mean checking account balance at the institution:
$2183 < u < $3828.
Interpret this confidence interval.

a. If we took random samples of checking accounts at this credit union, about nine out of ten of them would produce this confidence interval.
b. We are 90% sure that the mean balance for checking accounts in the sample was between $2183 and $3828.
c. We are 90% confident that the mean checking account balance at this credit union is between $2183 and $3828, based on this sample.
d. About 9 out of 10 people have a checking account balance between $2183 and $3828.
e. We are 90% confident that the mean checking account balance in the U.S. is between $2183 and $3828.