Kathy’s customer base is 2/3 residential and 1/3 business if she has 350 residential customers how many total customers does she have

Hi my sisters and brothers can tell me the answer because i don’t understand the question

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.

If you measured the width of a window in inches and then in feet with measurement would you have the greater number of units