1. **Problem statement:** We have a group of students consisting of 3 freshmen, 10 sophomores, 5 juniors, and 6 seniors. We want to find the probability of choosing exactly 3 seniors when selecting 5 members at random for a committee.
2. **Total number of students:**
$$3 + 10 + 5 + 6 = 24$$
3. **Total ways to choose 5 members from 24:**
We use combinations since order does not matter:
$$\binom{24}{5}$$
4. **Number of ways to choose exactly 3 seniors:**
Choose 3 seniors from 6:
$$\binom{6}{3}$$
5. **Number of ways to choose the remaining 2 members from non-seniors:**
Non-seniors count:
$$3 + 10 + 5 = 18$$
Choose 2 from these 18:
$$\binom{18}{2}$$
6. **Number of favorable outcomes:**
$$\binom{6}{3} \times \binom{18}{2}$$
7. **Probability formula:**
$$P(\text{exactly 3 seniors}) = \frac{\binom{6}{3} \times \binom{18}{2}}{\binom{24}{5}}$$
8. **Calculate each combination:**
$$\binom{6}{3} = \frac{6 \times 5 \times 4}{3 \times 2 \times 1} = 20$$
$$\binom{18}{2} = \frac{18 \times 17}{2 \times 1} = 153$$
$$\binom{24}{5} = \frac{24 \times 23 \times 22 \times 21 \times 20}{5 \times 4 \times 3 \times 2 \times 1} = 42504$$
9. **Calculate numerator:**
$$20 \times 153 = 3060$$
10. **Calculate probability:**
$$P = \frac{3060}{42504}$$
11. **Simplify fraction:**
Divide numerator and denominator by 12:
$$\frac{\cancel{12}255}{\cancel{12}3542}$$
So,
$$P = \frac{255}{3542} \approx 0.072$$
**Final answer:** The probability of choosing exactly 3 seniors is approximately **0.072** or **7.2%**.
Probability 3 Seniors 326720
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