Answer:
Zero probability that more than 4 need to be returned.
Explanation:
The return rate is (3/500) or 0.6 %.
That would mean that 200 calculators would be predicted to have:
(300 calculators)*(0.006) = 1.8, or 2 that need to be returned.
We are told to "Calculate the probability that more than 4 out of this purchase are returned immediately." Since we calculate only 2 will need to be returned out of the 200 purchased, the probability of more than 4 needing return is close to zero. Without additional information on the original probability, the best answer here is zero. More information is needed on the distribution probability of the past experience - i.e., Over four years of collecting data on rejection rate, we could establish a probability that might read something like a return rate of 0.6% ± 10%. This would allow a more realistic estimate on the predicted return rate of over 4 on 200 calculators.