Point Estimate, Margin of Error and Confidence Level

[bunnypatotie]

1. One of the few negative effects of quitting smoking is weight gain. The data below shows the weight gain (in pounds) of 18 respondents 12 months after they quit. If the mean gain follows a normal distribution with a standard deviation of 9 pounds, estimate the mean weight gain of the 18 respondents at a 95% confidence level.

14 13 20 22 12 12 17 10 12 9 11 17 15 24 29 13 13 19​

 

[Kansas Boy]

Okay, that's a pretty straightforward problem. Do you know how to find the average of 18 numbers?