Astudent missed 16 problems on a biology test and received a grade of 33 %. if all the problems were of equal value, how many problems were on the test? round off your answer to the nearest integer.

Just tell me how to set up the equation.

Me. i can't figure out this question. give an explanation too. .

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.