11) 12C2
2) 15C10 / 30C2
\hspace{-16}(1)\;\; $Total no. of Selecting $\mathbf{10}$ Balls from an Unlimited no. of Identical\\\\ Red, Green and Yellow Balls is =$\\\\\\ (2)\;\; $There are $\mathbf{15}$ Matching pairs of Shocks in Drawer.\\\\ $\mathbb{V}$ivek Selected $\mathbf{10}$ Shocks from the drawer in a rush.\\\\ Then the Probability that there is no matching Pair is
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11 Answers
2621) R +G +B =10 ( R,G,B ≥0)
no. of solutions = 10 +3 -1C3-1 = 12C2
2) i am getting 210 . 15C530C10 ≈ 0.102
71Aditya or man111, could you post the complete solution for the second one?
1057for the 2nd one...
select 5 socks first.....it can be done in 30C5 ways.....now for the rest 5 we cant select any of the 5 matching pairs nd so now we have 20 options to pick 5 from...
therefore probability = 30C5 x 20C530C10
1ways of choosing 10 socks from 30= 30c10
ways of choosing correct pair of socks=10c5
ways of choosing incorrect socks=total-correct ways
=30c10-10c5
thus probability=30c10-10c530c10
is it correct?
1057@funkygp
the question is "no matching pair" but in your case it only eliminates the cases in which all are matching pairs...u also have to eliminate the cases in which there are 4,3,2 and 1 matching pair(s)....
1@ketan when you select 5 socks first, in that itself there can be matching pairs
my solution,
since there has to be no matching pair => from any of the 15 pairs we can take atmost 1.
=> total number of ways is nothing but selecting 10 out of 15
=> 15C10 / 30C10
