Jessica Probability Edafe4
1. **State the problem:** Jessica has a probability of $\frac{4}{5}$ of getting an A in Mathematics and a probability of $\frac{2}{5}$ of getting an A in English. We want to find the probability that Jessica gets exactly one A in the two subjects.
2. **Represent the problem with a tree diagram:**
- First branch: Mathematics A with probability $\frac{4}{5}$, Mathematics not A with probability $\frac{1}{5}$.
- Second branch (from each Mathematics outcome): English A with probability $\frac{2}{5}$, English not A with probability $\frac{3}{5}$.
3. **Calculate the probabilities of each combined outcome:**
- Both A: $\frac{4}{5} \times \frac{2}{5} = \frac{8}{25}$
- Math A, English not A: $\frac{4}{5} \times \frac{3}{5} = \frac{12}{25}$
- Math not A, English A: $\frac{1}{5} \times \frac{2}{5} = \frac{2}{25}$
- Neither A: $\frac{1}{5} \times \frac{3}{5} = \frac{3}{25}$
4. **Find the probability of exactly one A:**
This happens if Jessica gets A in Mathematics but not in English, or not in Mathematics but A in English.
$$P(\text{one A}) = \frac{12}{25} + \frac{2}{25} = \frac{14}{25}$$
5. **Conclusion:** The probability that Jessica gets exactly one A in the two subjects is $\frac{14}{25}$ or 0.56.