There are three piles of identical yellow, black and green balls and each pile contains at least $20$ balls.
The number of ways of selecting $20$ balls if the number of black balls to be selected is twice the number of yellow
balls, is

Question

Infinity Learn · Accepted Answer

Let the number of yellow balls be x, that ofblack be $$2x$$ and that of green be y. $$Thenx+2x+y=20$$ or $$3x+y=20$$ ⇒  $$y=20$$−$$3x$$ As $$0$$≤y≤$$20$$, we get $$0$$≤$$20$$−$$3x$$≤$$20$$⇒ $$0$$≤$$3x$$≤$$20$$ or $$0$$≤x≤$$6$$∴ The number of ways of selecting the balls is $$7$$.

There are three piles of identical yellow, black and green balls and each pile contains at least $20$ balls.
The number of ways of selecting $20$ balls if the number of black balls to be selected is twice the number of yellow
balls, is

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There are three piles of identical yellow, black and green balls and each pile contains at least 20 balls.The number of ways of selecting 20 balls if the number of black balls to be selected is twice the number of yellowballs, is

Remember concepts with our Masterclasses.

Ready to Test Your Skills?

free study material

There are three piles of identical yellow, black and green balls and each pile contains at least $20$ balls.
The number of ways of selecting $20$ balls if the number of black balls to be selected is twice the number of yellow
balls, is