Answered>Order 651

A machine to detect improper welds in a fabricating shop detects 80 percent of all improper

welds, but it also incorrectly indicates an improper weld on 5 percent of all satisfactory welds.

Past experience indicates that 10 percent of all welds are improper.

i. What is the probability that a weld that the machine indicates to be defective is in fact

satisfactory?

ii. What is the probability that a weld which the machine indicates to be satisfactory is in fact

defective?

iii. Compare the probabilities in (a) and (b) and comment on their relative magnitudes.