1. The problem asks to find the probability $P(M \cap B)$ using the given tree diagram. 2. According to the multiplication rule for probabilities in a tree diagram, the probability of both events $M$ and $B$ occurring is: $$P(M \cap B) = P(M) \times P(B|M)$$ 3. From the tree diagram: - $P(M) = 0.9$ - $P(B|M) = 0.7$ 4. Calculate the probability: $$P(M \cap B) = 0.9 \times 0.7$$ 5. Multiply the values: $$P(M \cap B) = 0.63$$ 6. Therefore, the probability $P(M \cap B)$ is 0.63.