Question

A box contains 12 transistors, 3 of which are defective. If 3 are selected at random, find the probability?

All are Defective =
None are defective=

Answer 1

P(all are defective) = (3/12)^3 = (1/4)^3 = 1/64
P(none are defective) = (9/12)^3 = (3/4)^3 = 27/64