Katherine spends 7 h a day in school. this includes a 30 min lunch break each day. a) write a ratio that compares the time for her lunch break with the total time she spends at school each day. b) write a ratio that compares the time for her lunch breaks for a week with the total time she spends at school each week. c) determine the number of hours of lunch break she has in a month of school 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.