JEE MainMathematicsPermutations and CombinationsMCQ+4 / −1
Assuming the balls to be identical except for difference in colours, the number of ways in which one or more balls can be selected from 10 white, 9 green and 7 black balls is:
- A880
- B629
- C630
- D879
View written solutionFree
Correct answer: D
-
Since balls of the same colour are identical, a selection is completely determined by how many white, green, and black balls are chosen.
-
Let
- = number of white balls chosen, where
- = number of green balls chosen, where
- = number of black balls chosen, where
-
The number of choices for each colour is:
- White: choices ( to )
- Green: choices ( to )
- Black: choices ( to )
-
Hence, total number of selections including the empty selection is
-
But the question asks for selection of one or more balls, so exclude the case where no ball is selected:
-
Therefore, the correct option is
-
Comparing with the stored correct answer:
- Stored answer: D
- Option D =
- This matches our result.
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