At a competition with 7 runners, 2 medals are awarded for first and second place.Each medal is different. How many ways are there to award the medals?A.21B.5040C.49D.42SUBMITarrow_backPREVIOUS
Question
At a competition with 7 runners, 2 medals are awarded for first and second place.Each medal is different. How many ways are there to award the medals?A.21B.5040C.49D.42SUBMITarrow_backPREVIOUS
Solution
The problem can be solved using the concept of permutations.
In this case, we have 7 runners and we want to know in how many ways we can award 2 different medals (for first and second place).
This is a permutation problem because the order in which the medals are awarded matters (a first place is not the same as a second place).
The formula for permutations is:
P(n, r) = n! / (n-r)!
where:
- n is the total number of items,
- r is the number of items to choose,
- "!" denotes factorial, which is the product of all positive integers up to that number.
So, in this case, we have:
P(7, 2) = 7! / (7-2)!
Calculating the factorials:
7! = 7 * 6 * 5 * 4 * 3 * 2 * 1 = 5040 5! = 5 * 4 * 3 * 2 * 1 = 120
So,
P(7, 2) = 5040 / 120 = 42
Therefore, there are 42 ways to award the medals. So, the answer is D.42.
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