The flywheel on a steam engine rotates 60 revolutions every 15 seconds. What is the flywheel’s rate of revolutions per second? ( can somebody tell me what the unit rate and the rate unit is)

15 point ! ~ see if you know the answer to both you!

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.

Are the corresponding angles congruent? explain why or why not.