Two cars leave phoenix and travel along roads 90 degrees apart. if car 1 leaves 30 minutes earlier than car 2 and averages 42 mph and if car 2 averages 50 mph, how far apart will they be after car 1 has traveled 3.5 hours?
a: 230
b: 250
c: 210

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.