What is the sum? a.)9+(-11) +(-8) +2 d.)1/8+(-2/3)

Factor the expression using the gcf. the expression 21m−49n factored using the gcf

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.

Can you me find the missing length. i attached an image.