If the question is how many shelves are needed, then the answer is 18 shelves.
For the given situation we have a total of 259,459,200 permutations.
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How many permutations are?</h3>
First, how we know that it is a permutation?
Because the order matters, we aren't only selecting 8 out of the 15 people, but these 8 selected also have an order (is not the same thing to finish the race first than fourth, for example).
Then we need to find the number of permutations, to do it, we need to find the numbers of options for each of the 8 positions.
- For the first position there are 15 options.
- For the second position ther are 14 options (one runner already finished).
- For the third position there are 13 options.
- And so on.
Then the total number of permutations (product between the numbers of options) is:
P = 15*14*13*12*11*10*9*8 = 259,459,200
If you want to learn more about permutations:
brainly.com/question/11732255
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I am not for sure that what im about to type is the right answer but if im not wrong the amswer is 1over4
answers on on paper I did, good luck with literal equations I know they suck, just know to use inverse operations and these problems are basically normal problems replaced with variables instead.