1.

If nPr = 1680 and nCr = 70, find n and r.

Answer»

Given that nPr = 1680, nCr = 70 

We know that nCr\(\frac{nP_r}{r!}\)

70 = \(\frac{1680}{r!}\)

r! = \(\frac{1680}{70}\) = 24 

r! = 4 x 3 x 2 x 1 = 4! 

∴ r = 4



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