30 points statistics! students at a university were surveyed about when they registered for classes. the results of the survey are shown in the table. if a student registered early, find the probability that the student is an undergraduate. registered early registered on time undergraduate 211 347 graduate 329 581 a. 0.608 b. 0.391 c. 0.144 d. 0.374

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.