The Total solution for NCERT class 6-12
If 15Cr: 15Cr – 1 =11: 5, find r.
Given:
15Cr: 15Cr – 1 =11: 5
15Cr / 15Cr– 1 = 11 / 5
Let us use theformula,
nCr = n!/r!(n – r)!
5(16 – r) = 11r
80 – 5r = 11r
80 = 11r + 5r
16r = 80
r = 80/16
= 5
∴ The value of ris 5.