two methods A and B are available for teaching a certain ind

two methods, A and B are available for teaching a certain industrial skill. The failure rate is 20% for A and 10% for B. However, B is more expensive and is used only 30% of the time. A worker was taught the skill by one of the methods but failed to learn it correctly. What is the probability that she was taught by method A?

Solution

The failure rate is 20% for A and 10% for B. However, B is more expensive and is used only 30% of the time.

Thus, the probability that a worker who taught the skill by one of the methods but failed to learn it correctly was taught by method A is:

0.2*(1-0.3)

=0.14