Permutations or combinations? Permutations Answer: 5040
Practice makes perfect
We want to find how many ways there are to choose four out of 10 different runners. Note that, in this case, the order is important. Thus, each possible arrangement is a permutation. To calculate the answer, we will use the formula for permutations of n runners taken r at a time.
_n P_r = n!/(n-r)!
We have ten finalists and are taking four at a time. This means that n= 10 and r= 4. Let's substitute 10 for n and 4 for r in the above formula.
