if ^{\n}\P_{\r} = 720 and ^{\n}\C_{\r} = 6, then find value of r! ?

Haryana Police Constable Model Paper 3

Question : 50 of 100

Marks: +1, -0

^{\n}\P_{\r}

= 720 and

^{\n}\C_{\r}

= 6, then find value of r! ?

Solution:

Formula Used:

^{\n}{\P_{\r}}=\n ! /(\n-\r) !

^{\n}\C_{\r} = \n ! /[( \n - \r ) ! \r !]

{{^{\n}\P _{ \r }} /{ ^{\n}\C _{ \r }}

\r !

Calculation:
Given:

{^{\n}\P _{ \r }

720

{^{\n}\C _{ \r }

6

{{^{\n}\P _{ \r }} /{{^{\n}\C _{ \r }}

\r !

\r !

720/6

\r !

120

\r !

5×4×3×2×1

\r = 5

∴ The value of

\r !

5!

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