If your chemistry grade is broken down so that 70% of it is exams, 20% is a lab, and 10% is homework, and your average scores out of 100 points in each area are:

exams 85
labs 75
homework 96
calculate your weighted average.

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.