Two teaching methods, A and B, are implemented for learning Spanish. There is a 70% chance of successfully learning Spanish if method A is used, and a 85% chance of success if method B is used. However, method B is substantially more time consuming and is therefore used only 20% of the time (method A is used the other 80% of the time). The following notations are suggested

• AMethod A is used.
• BMethod B is used.
• LSpanish was learned successfully.

What is the probability that a randomly chosen person will learn Spanish successfully?

1. a-P(L) = 0.20 * 0.85 = 0.1700
2. P(L) = 0.80 * 0.70 = 0.5600
3. P(L) = 0.80 * 0.70 + 0.20 * 0.85 = 0.7300
4. P(L) = 0.80 * 0.85 + 0.20 * 0.70 = 0.8200
5. P(L) = 0.80 * 0.20 + 0.70 * 0.85 = 0.7550