need help with this whole question

1. The average weight of 6 people in an elevator is 173 pounds. A 7th person gets on and now the average weight is 165 pounds. How much did the 7th person weigh? 2. Use the following data obtained from ages of the last six U. S. Presidents at the time of their inauguration to answer the followin_ a uestions: at Inau_ uration _-El a. Find the mean of the data set. [Round to one decimal place.) b. Find the standard deviation of the data set. [Do not round until the nal answer. Round final answer to 1 decimal place.) c. What percentage of presidents' ages fall within one standard deviation of the mean? [Round to 1 decimal place.)