A mutual fund manager is trying to estimate the expected fund flows for the next quarter. To make the estimate, the manager calls 15 clients and asks each of them about their planned deposits/withdrawals from the fund. The asset-weighted average of the sample is a 4.2 % change in assets under management, with a standard deviation of 10 %. What is the width of the 95% confidence interval for next quarter's fund flows? Enter answer in percents, accurate to two decimal places. The answer is 11.8 please help me get to that number