If 6Pr = 360 and If 6Cr = 15, find r ?

nPr = nCr × r! 6Pr = 15 × r! 360 = 15 × r! r! = 36015 = 24 r! = 4 × 3 × 2 × 1 ⇒ r! = 4! Therefore, r = 4

Home

Competitive Exams

Computer & Programming

Other Subjects

Exam Categories

SSC Exams Railway Exams All Exams

Popular Exams

Engineering Subjects

More Engineering

Engineering Core

Computer Fundamentals

Programming

Advanced

Graduation & PG

Resources

Current Affairs Interview Blog

This question belongs to Arithmetic Ability Permutation And Combination

Permutation and Combination

?

If ⁶P_r = 360 and If ⁶C_r = 15, find r ?

A) 5 B) 6 C) 4 D) 3

Answer & Solution

Correct Answer: Option C

ⁿP_r = ⁿC_r × r!
⁶P_r = 15 × r!
360 = 15 × r!
r! = $$\frac{{360}}{{15}}$$ = 24
r! = 4 × 3 × 2 × 1
⇒ r! = 4!
Therefore, r = 4

Question posted by Examveda

Community

Join the discussion

Login to post a comment or share your explanation.

No comments yet Be the first to discuss this question.

Keep Learning