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Question Number 115387 by bemath last updated on 25/Sep/20

Commented by bemath last updated on 25/Sep/20

p= ((^8 C_4 ×!4)/(8!)) = ((((8!)/(4!.4!)) × 9)/(8!)) = (9/(576))

$${p}=\:\frac{\:^{\mathrm{8}} {C}_{\mathrm{4}} ×!\mathrm{4}}{\mathrm{8}!}\:=\:\frac{\frac{\mathrm{8}!}{\mathrm{4}!.\mathrm{4}!}\:×\:\mathrm{9}}{\mathrm{8}!}\:=\:\frac{\mathrm{9}}{\mathrm{576}} \\ $$$$ \\ $$

Commented by bemath last updated on 25/Sep/20

Sir W it is correct ?

$${Sir}\:{W}\:{it}\:{is}\:{correct}\:? \\ $$

Commented by mr W last updated on 25/Sep/20

correct!  p= ((^8 C_4 ×!4)/(8!)) = ((((8!)/(4!.4!)) × 9)/(8!)) = (9/(576))=(1/(64))

$${correct}! \\ $$$${p}=\:\frac{\:^{\mathrm{8}} {C}_{\mathrm{4}} ×!\mathrm{4}}{\mathrm{8}!}\:=\:\frac{\frac{\mathrm{8}!}{\mathrm{4}!.\mathrm{4}!}\:×\:\mathrm{9}}{\mathrm{8}!}\:=\:\frac{\mathrm{9}}{\mathrm{576}}=\frac{\mathrm{1}}{\mathrm{64}} \\ $$

Commented by indalecioneves last updated on 30/Sep/20

I didn′t understand why  you multiplied by 9.

$${I}\:{didn}'{t}\:{understand}\:{why}\:\:{you}\:{multiplied}\:{by}\:\mathrm{9}. \\ $$$$ \\ $$$$ \\ $$

Commented by mr W last updated on 30/Sep/20

!4=9

$$!\mathrm{4}=\mathrm{9} \\ $$

Commented by indalecioneves last updated on 01/Oct/20

Oh, yes, chaotic permutation.   I haven′t solved exercises with this theme  for a long tine. Thanks, Sir.

$${Oh},\:{yes},\:{chaotic}\:{permutation}.\: \\ $$$${I}\:{haven}'{t}\:{solved}\:{exercises}\:{with}\:{this}\:{theme} \\ $$$${for}\:{a}\:{long}\:{tine}.\:{Thanks},\:{Sir}. \\ $$

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