Show detailed steps with excel As a store manger you would like to find out the average time it takes to unload the truck which delivers the merchandise for your store. For this purpose, you have taken a random sample of 35 days and found the average unload time to be 263 minutes for the sample. You also found that the standard deviation is 45 minutes for the sample. Find the upper boundary of the 95% confidence interval for the average unload time. Round the answer to two decimal places.