Tamil Nadu Board of Secondary EducationHSC Commerce Class 11

If nPr = 720(nCr), then r is equal to: - Business Mathematics and Statistics


If nPr = 720(nCr), then r is equal to:


  • 4

  • 5

  • 6

  • 7





Given nPr = 720(nCr)

`(n!)/((n-r)!) = 720 (n!)/(r!(n-r)!)`

1 = `720/(r!)`

r! = 720

r! = 6 × 5 × 4 × 3 × 2 × 1

r! = 6!

r = 6

Concept: Combinations
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Chapter 2: Algebra - Exercise 2.7 [Page 46]


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