A statistician is trying to uncover spending habits of shoppers at a local grocery store. He samples 7 shoppers at random and determines how much they spent on groceries at their last visit (to the nearest dollar). Results are as follows: Amount spent: $105, $75, $108, $128, $86, $165, $172 Assume that the amount spent per grocery store visit is normally distributed. a) (8pts) Compute the sample mean, the sample median, the sample variance, and the sample standard deviation of the amount spent on groceries in the sample. (Round answers to 4 decimal points except for the variance, which you can round to 2 decimal points) Mean: $ Median: $ Variance: SD: S b) (4pts) Compute a 95% confidence interval for the population mean u for the average amount a shopper spends during a visit to this grocery store. (Round answers to 4 decimal points) to $