Question

If 16P(r-1):15P(r-1)=16:7 permutation example probablity pls explain its ans 10

Answer 1

Answer:

answer is 10

Step-by-step explanation:

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Answer 2

Solve $\ ^{16}P_{r-1}\ :\ ^{15}P_{r-1}\ =16:7$

• $\ ^{16}P_{r-1}=\dfrac{16!}{(16-r+1)!}$
• $\ ^{15}P_{r-1}=\dfrac{15!}{(15-r+1)!}$

$\dfrac{16!}{(16-r+1)!}:\dfrac{15!}{(15-r+1)!}=16:7$

$\dfrac{16}{(16-r+1)!}:\dfrac{1}{(15-r+1)!}=16:7$

$7\times\dfrac{16}{(16-r+1)!}=16\times\dfrac{1}{(15-r+1)!}$

$7\times\dfrac{1}{(16-r+1)!}=1\times\dfrac{1}{(15-r+1)!}$

$\dfrac{(16-r+1)!}{(15-r+1)!}=7$

$16-r+1=7$

$r=10$