Nikko needs to get his air-conditioner fixed. The repairman will charge Nikko a flat fee of $50 plus an additional $20 for each hour he needs to work on it.
Write an equation to represent Nikko's total cost to repair his air-conditioner. Use t for total
cost and h for hours.

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.