Question

If 28Cr:26cr-2=18:5 then the value of r is​

Answer 1

Answer:

nCr = n! / r! (n-r)!

28Cr = 28! / r! (28-r)!

26C(r-2) = 26! / (r-2)!(26 - (r-2))!

= 26! / (r-2)!(28-r)!

Given :-

28Cr / 26C(r-2) = 18/5

(28!/r!(28-r)! )((r-2)!(28-r)! / 26! = 18/5

27×28(r-2) / r = 18/5

3780r - 7560 = 18r

3762r = 7560

r = 3880 / 1881