what conditions on (positive) numbers a, b,c, and d will guarantee that every difference at every step in the expansion (a-b)(c-d) results in a positive number

Atrucker had a load of grain containing 2 tons. she unloaded 1 ton and 1,200 pounds at the warehouse. how much grain does she still have left on the truck?

Tcan be concluded that % of the seniors would prefer to see more candid pictures in this year's edition of the yearbook.

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.