Question

Suppose the average annual expense for a random sample of 12 stock funds is normally distributed with mean of 1.63 percent with a standard deviation of .31 percent. Calculate a 95 percent confidence interval for the mean annual expense charged by all stock funds.

Answer 1

The confidence interval is found by plugging the given values into the following:
\[\large (\bar{x}-1.96\frac{\sigma}{\sqrt{n}},\ \bar{x}+\frac{\sigma}{\sqrt{n})})\]

Answer 2

Giving:
\[\large CI=(1.63-1.96\frac{0.31}{\sqrt{12}},\ 1.63+1.96\frac{0.31}{\sqrt{12}})=you\ can\ calculate\]

Answer 3

@work12345 Are you there?

Answer 4

@kropot72 thanks a lot for your help! Sorry about that, I left my computer after waiting awhile on this question.

Answer 5

You're welcome :)