Question

There are 4 red, 3 green and five blue discs.two discs are drawn out. Find probability that two discs of same color are drawn out

Answer 1

There are 4 red, 3 green and five blue discs.

Total number of discs = 4 + 3 + 5 = 12

Number of ways of drawing 2 discs from 12 discs = $12\raisebox{0.25em}{$C$}2$

If two discs are drawn out then the probability that two discs of same color are drawn out is:

$P=\frac{(4\raisebox{0.25em}{$C$}2)+(3\raisebox{0.25em}{$C$}2)+(5\raisebox{0.25em}{$C$}2)}{12\raisebox{0.25em}{$C$}2}$

$P=\frac{2.92}{66}=0.044$

There is 4.4 percent probability that two discs of same color are drawn out from 12 discs.