Tom fed his chickens with grains on Sun. The chickens ate a 1/4 of what was given to them that day. On Mon, the chickens ate a 1/4 of what's left from Sun night. What fraction of the original food was left on Monday night after the chickens went to bed?

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.