P(defective) = 3/12 = 1/4
P(good) = 1 - 1/4 = 3/4



The probability that at least 2 units are good is given by:
P(2 good) + P(3 good) + P(4 good) = 0.211 + 0.422 + 0.316 = 0.949.
27 because the square root of 81 is 9 and 9 times 3 is 27.
Really bad according to the BLS, the average secondary school teacher in the U.S. earns an annual salary of $56,760. A 40-hour work week employee would have to earn $27.28 per hour to earn as much over the course of a year.
35 would be positive while 40 would be negative