Again we have two methods, A and B, available for teaching a certain industrial skill. There is a 75% chance of successfully learning the skill if method A is used, and a 95% chance of success if method B is used. However, method B is substantially more expensive and is therefore used only 20% of the time (method A is used the other 80% of the time).

What is the probability that a randomly chosen worker will learn the skill successfully?

1. P(L) = .80 * .75 = .60
2. P(L) = .20 * .95 = .19
3. P(L) = .80 * .95 + .20 * .75 = .91
4. P(L) = .80 * .75 + .20 * .95 = .79
5. P(L) = .80 * .20 + .75 * .95 = .8725