If a year only had 364 days then we could use the same calendar every year. but actually most years have 365 days, and a leap year has 366 days. for the relevant years, a leap year occurs when the year is divisible by 4
i was just about to throw my calendar away for 2013 when i wondered when i would first be able to reuse it. in which year would that be? justify your answer.

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.