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 15% of the time (method A is used the other 85% of the time). The following notations are suggested: . A-Method A is used. . B-Method B is used. . L-Spanish was learned successfully. A person learned Spanish successfully. What is the probability that he was taught by method A? O (0.15 * 0.85)/(0.85 * 0.70 + 0.15 * 0.85) = 0.1765 O 0.70 O (0.85 * 0.70)/(0.85 * 0.70 + 0.15 * 0.85) = 0.8235 O (0.85 * 0.70)/(0.70 + 0.85) = 0.3839 O 0.85 * 0.70 = 0.5950