Answer:
35 different groups of 3 runners can be selected
Explanation:
Here, we want to simply calculate the number of 3 runners that can advance in a race from a total of 7
What we want to do here is to simply get different groups of 3
So, we have it that we simply want to know the number of different ways we can select 3 from a total of 7
We can simply use combination for this;
We have the general combinatorial as;
nCr = n!/(n-r)!r!
With respect to this particular question, n = 7 and r = 3
So we have;
7C3 = 7!(7-3)!3! = 7!/(4)!3! = 35