A machine produces widgets at a defective rate of 9%. A sample of 11 widgets is taken, What is the probability that 3 of them are defective?

Question

A machine produces widgets at a defective rate of 9%. A sample of 11 widgets is taken, What is the probability that 3 of them are defective?

A. 0.0559

B. 0.0566

C. 0.1427

D. 0.1639

Answer 1

11C3(.09)^3(.91)^8

11C3 = 11/3!8! =11x10x9/3x2 = 165

.09^3 = .000729

.91^8 = about .47

165 x 00729 x .47 = 0.0565

B is correct