Permutation.
nC2 = 190
n!
------- = 190
n-2! 2!
n (n-1)
-------- = 190
2
n^2 - n = 380
n^2 - n - 380 = 0
n = 20, 18.
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kuroneko1313
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Consider this:pre-gmat wrote:How did u get this part?
n (n-1)
-------- = 190
2
n! = n (n-1) (n-2)!
As posted by anshul265:
n!
------- = 190
n-2! 2!
n (n-1) (n-2)!
----------------- = 190
n-2! 2!
now the (n-2)! gets canceled out by the denominator, leaving only n (n-1) at the top. Hope that helps.
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raju232007
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there are 190 possible selections to select 2 people from n members
so nC2=190
i.e n!/2!((n-2)!=190
n!=380(n-2)!
w.k.t n!=n*(n-1)*(n-2)!
n*(n-1)*(n-2)!=380(n-2)!
n(n-1)=380
Solving this we get n=20
so nC2=190
i.e n!/2!((n-2)!=190
n!=380(n-2)!
w.k.t n!=n*(n-1)*(n-2)!
n*(n-1)*(n-2)!=380(n-2)!
n(n-1)=380
Solving this we get n=20
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vishubn
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i plugged in numbers
ANd got the answer with
nC2=190
where n is the number of people wanting to be filled for two slots !
20 possiblity for the first slot and 19 for the second !
as it says differnt number of ways its combi
20*19/2*1 = 10* 19=190
Vishu
ANd got the answer with
nC2=190
where n is the number of people wanting to be filled for two slots !
20 possiblity for the first slot and 19 for the second !
as it says differnt number of ways its combi
20*19/2*1 = 10* 19=190
Vishu
