Smith is a weld inspector at a shipyard. He knows from keeping track of good and substandard welds that forthe afternoon shift 5% of all welds done will be substandard. If Smith checks 300 of the 7500 welds completedthat shift, what is the probability that he will find more than 25 substandard welds?
A) 0.0040
B) 0.4960
C) 0.5040
D) 0.9960

Question

Quizplus · Accepted Answer

This is a binomial probability problem where the number of trials is 300, the probability of success (finding a substandard weld) is 0.05, and we want to find the probability of having more than 25 successes. The exact calculation of this probability can be complex, but using normal approximation or a binomial probability calculator, we find that the probability of finding more than 25 substandard welds is very low, hence option A (0.0040) is correct. This indicates that it is quite unlikely for Smith to find more than 25 substandard welds among the 300 he checks, given the 5% substandard rate.

Smith Is a Weld Inspector at a Shipyard