Question

A store has 80 modems in its inventory, 30 coming from source a and the remainder from source

Answer 1

The number of defective modems in the inventory is 20%⋅ 30 + 8%⋅ 50 = 10 (out of 80). Note that the number of defectives in the inventory is fixed, i.e., we are not told that there is 1 8 probability that a modem in the inventory is defective, but rather that exactly 1 8 of all modems are defective. The probability that exactly two modems in a random sample of five are defective is = 0.102