Answer :

Given, nCr–1 = 36, nCr = 84 and nCr+1 = 126


To find:r=?





3(n-r+1)=7r


3n-10r=-3….(1)





2(n-r)=3(r+1)


2n-5r=3….(2)


From equations 1 & 2 we get


n=9 & r=3


Ans:r=3


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses
RELATED QUESTIONS :

Prove that the prRD Sharma - Mathematics

There are 10 lampMathematics - Exemplar

If n+1RS Aggarwal - Mathematics

If nC<RS Aggarwal - Mathematics

Fill in the BlankMathematics - Exemplar

Fill in the BlankMathematics - Exemplar

The number of wayMathematics - Exemplar

Total number of wMathematics - Exemplar

The number of wayMathematics - Exemplar

The number of triMathematics - Exemplar