If I can paint a wall in 20 min and my friend can paint a wall in 30 min. How many minutes would it take for us to paint a wall working together.

Amajor grocery store chain is trying to cut down on waste. currently, they get peaches from two different distributors, whole fruits and green grocer. out of a two large shipments, the manager randomly selects items from both suppliers and counts the number of items that are not sell-able due to bruising, disease or other problems. she then makes a confidence interval. is there a significant difference in the quality of the peaches between the two distributors? 95% ci for pw-pg: (0.064, 0.156)