From a group of persons the number of ways of selecting 5 persons is equal to that of 8 persons. No of ways of selecting 2 persons is.....
The number of ways of selecting r person out of n is nCr
As per your question we can write mathematically the given condition in the form of equations as shown below
nC5=nC8
Where n is the number of persons
On solving
n=13
Now the required answer can be found by calculating 13C2
Therefore 13C2=78