Fruit Probabilities D3A4Ec
1. **State the problem:** Jim has 9 pieces of fruit: 7 grapefruits and 2 apples. He picks one fruit at random and eats it, then picks a second fruit at random. We want to find the probabilities labeled A and B on the probability tree for the second pick after the first pick was an apple.
2. **Understand the tree:**
- First pick: 7/9 chance grapefruit, 2/9 chance apple.
- If first pick grapefruit: second pick probabilities are 6/8 grapefruit and 2/8 apple (since one grapefruit is eaten, 6 grapefruits left out of 8 total fruits left).
- If first pick apple: second pick probabilities are unknown (A for grapefruit, B for apple).
3. **Calculate A and B:**
- After eating one apple, remaining fruits: 7 grapefruits and 1 apple (total 8 fruits).
- Probability second pick is grapefruit (A) = number of grapefruits left / total fruits left = $\frac{7}{8}$.
- Probability second pick is apple (B) = number of apples left / total fruits left = $\frac{1}{8}$.
4. **Summary:**
- $A = \frac{7}{8}$
- $B = \frac{1}{8}$
These fractions are already in simplest form.
**Final answer:**
$$A=\frac{7}{8},\quad B=\frac{1}{8}$$