1. **Problem Statement:**
We have three girls Aisha, Betty, and Cate packing juice bottles. The probabilities that a crate is packed by Aisha, Betty, and Cate are 55%, 30%, and 15% respectively.
The probabilities that a crate packed by Aisha, Betty, and Cate is broken are 0.7, 0.2, and 0.1 respectively.
We want to find the probability that a crate with broken bottles was packed by Aisha using Bayes' theorem.
2. **Bayes' Theorem Formula:**
$$P(A|B) = \frac{P(B|A) \times P(A)}{P(B)}$$
where:
- $P(A|B)$ is the probability that Aisha packed the crate given it is broken.
- $P(B|A)$ is the probability the crate is broken given Aisha packed it.
- $P(A)$ is the probability that Aisha packed the crate.
- $P(B)$ is the total probability that a crate is broken.
3. **Given values:**
$$P(A) = 0.55, \quad P(B|A) = 0.7$$
$$P(Betty) = 0.30, \quad P(B|Betty) = 0.2$$
$$P(Cate) = 0.15, \quad P(B|Cate) = 0.1$$
4. **Calculate total probability of broken crate $P(B)$ using law of total probability:**
$$P(B) = P(B|A)P(A) + P(B|Betty)P(Betty) + P(B|Cate)P(Cate)$$
$$= 0.7 \times 0.55 + 0.2 \times 0.30 + 0.1 \times 0.15$$
$$= 0.385 + 0.06 + 0.015 = 0.46$$
5. **Apply Bayes' theorem:**
$$P(A|B) = \frac{0.7 \times 0.55}{0.46} = \frac{0.385}{0.46}$$
6. **Simplify fraction:**
$$P(A|B) = \frac{\cancel{0.385}}{\cancel{0.46}} = 0.837$$
**Final answer:**
The probability that a crate with broken bottles was packed by Aisha is approximately **0.837** or **83.7%**.
Bayes Broken Crate Ec4475
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