1. **State the problem:** We are given probabilities related to rain and flight delays at LaGuardia Airport. We want to find the probability that it is raining given that the flight has been delayed, i.e., $P(\text{Rain} \mid \text{Delayed})$.
2. **Given data:**
- $P(\text{Rain}) = 0.17$
- $P(\text{Delayed}) = 0.11$
- $P(\text{No Rain and On Time}) = 0.74$
3. **Important rules and formulas:**
- The total probability must sum to 1:
$$P(\text{Rain and Delayed}) + P(\text{Rain and On Time}) + P(\text{No Rain and Delayed}) + P(\text{No Rain and On Time}) = 1$$
- Conditional probability formula:
$$P(\text{Rain} \mid \text{Delayed}) = \frac{P(\text{Rain and Delayed})}{P(\text{Delayed})}$$
4. **Find $P(\text{No Rain})$:**
$$P(\text{No Rain}) = 1 - P(\text{Rain}) = 1 - 0.17 = 0.83$$
5. **Find $P(\text{No Rain and Delayed})$:**
Since $P(\text{No Rain and On Time}) = 0.74$, and $P(\text{No Rain}) = 0.83$, then
$$P(\text{No Rain and Delayed}) = P(\text{No Rain}) - P(\text{No Rain and On Time}) = 0.83 - 0.74 = 0.09$$
6. **Find $P(\text{Rain and Delayed})$:**
Using total probability:
$$1 = P(\text{Rain and Delayed}) + P(\text{Rain and On Time}) + P(\text{No Rain and Delayed}) + P(\text{No Rain and On Time})$$
Also, $P(\text{Rain}) = P(\text{Rain and Delayed}) + P(\text{Rain and On Time}) = 0.17$
So,
$$P(\text{Rain and On Time}) = 0.17 - P(\text{Rain and Delayed})$$
Substitute all known values:
$$1 = P(\text{Rain and Delayed}) + (0.17 - P(\text{Rain and Delayed})) + 0.09 + 0.74$$
Simplify:
$$1 = 0.17 + 0.09 + 0.74 = 1.0$$
This confirms the probabilities are consistent but does not directly give $P(\text{Rain and Delayed})$.
7. **Use $P(\text{Delayed})$ to find $P(\text{Rain and Delayed})$:**
$$P(\text{Delayed}) = P(\text{Rain and Delayed}) + P(\text{No Rain and Delayed}) = 0.11$$
Substitute $P(\text{No Rain and Delayed}) = 0.09$:
$$0.11 = P(\text{Rain and Delayed}) + 0.09$$
$$P(\text{Rain and Delayed}) = 0.11 - 0.09 = 0.02$$
8. **Calculate the conditional probability:**
$$P(\text{Rain} \mid \text{Delayed}) = \frac{P(\text{Rain and Delayed})}{P(\text{Delayed})} = \frac{0.02}{0.11} \approx 0.1818$$
9. **Round to the nearest thousandth:**
$$\boxed{0.182}$$
Rain Delayed E8E164
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