Suppose you just received a shipment of twelve televisions. two of the televisions are defective. if two televisions are randomly selected, compute the probability that both televisions work. what is the probability at least one of the two televisions does not work?

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

The base of a triangle exceeds the height by 7 centimeters. if the area is 400 square centimeters, find the length of the base and the height of the triangle.

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.