1. **State the problem:** There are 10 contestants in a speech contest, and we want to find how many possible ways the first, second, and third presenters can be chosen from these contestants.
2. **Concept applied:** This is a permutation problem because the order in which the presenters are chosen matters (first, second, third).
3. **Formula for permutations:** The number of ways to arrange $k$ items out of $n$ is given by
$$P(n,k) = \frac{n!}{(n-k)!}$$
where $n!$ is the factorial of $n$.
4. **Apply the formula:** Here, $n=10$ and $k=3$, so
$$P(10,3) = \frac{10!}{(10-3)!} = \frac{10!}{7!}$$
5. **Calculate factorials:**
$$10! = 10 \times 9 \times 8 \times 7!$$
So,
$$P(10,3) = \frac{10 \times 9 \times 8 \times 7!}{7!}$$
6. **Cancel common factors:**
$$P(10,3) = 10 \times 9 \times 8$$
7. **Multiply:**
$$10 \times 9 = 90$$
$$90 \times 8 = 720$$
8. **Final answer:** There are **720** possible ways to pick the first, second, and third presenters from 10 contestants.
Presenter Selection Ec38Ad
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