Question

Out of 1,100 discs tested, 13 are defective. Estimate the number of defective discs in a batch of 41,000. A. about 485 discs B. about 970 discs C. about 4,850 discs D. about 49 discs

Answer 1

Sample size={1,100 discs) = all possible outcomes
P(defective discs) = 13/1100 = 0.0118
Expected number of defects over a lot of 41,000 is:

41,000 x P(defects) = 41,000 x 0.0118 = 485.5 ≈ 485 (Answer A)