Andrea can wash a car in 12 minutes. Morgan can wash a car in 6 minutes. How many minutes would it take them to wash a car if they work together?

Assume that the weights of quarters are normally distributed with a mean of 5.67 g and a standard deviation 0.070 g. a vending machine will only accept coins weighing between 5.48 g and 5.82 g. what percentage of legal quarters will be rejected? round your answer to two decimal places.