1.

Find the number of ways of selecting 9 balls from 6 red balls, 5 white balls and 5 blue balls if each selection consists of 3 balls of each choice?

Answer»

We have Number of red balls = 6 

Number of White balls = 6 

Number of blue balls = 6 

Since each selection consists of 3 balls of each = 11  colours, so 3 red balls can be selected out of 6 balls in 6C3 ways, 3 white balls out of 5 can be selected in 5C3 ways and 3 blue balls out of 5 can be selected in 5C3 ways 

∴ Required number of ways = 6C3 x 5C3 x 5C3 

= 20 x 10 x 10 = 2000 



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