Clark mows lawns for $8 each. He is able to mow 3 lawns a day. Part A: Let N represent the number of days Clark mows lawns. Write an expression to show how much money Clark can earn mowing lawns. Part B: Use the expression from Part A to show how much money Clark would earn if he mowed lawns for 7 days.

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.