The area of a circle increases at a rate of 1 cm^2/s. how fast is the radius changing when the circumference is 2 cm?

If you answer right ill give brainliest, : )

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.

Paul’s car is 18 feet long. he is making a model of his car that is 1/6 the actual size. what is the length of the model?