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

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)