A random sample of 16 pharmacy customers showed the waiting time in in minutes as follows: 21, 22, 14, 17, 20, 25, 19, 16, 22, 16, 14, 17, 26, 19, 12, 18.

Find a 90% confident interval for (symbol looks like a backwards y) assuming the sample is from a normal population.

The 90% confidence interval is: ??