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Science & Technology·Easy

A bag contains 20 balls. 8 balls are green, 7 are white and 5 are red. What is minimum number of balls that must be picked up from the bag blind-folded (without replacing any of it) to be assured of picking at least one ball of each colour?

A bag contains 20 balls. 8 balls are green, 7 are white and 5 are red. What is minimum number of balls that must be picked up from the bag blind-folded (without replacing any of it) to be assured of picking at least one ball of each colour?

Options

  1. a.

    4

  2. b.

    7

  3. c.

    11

  4. d.

    16

    Correct answer

Explanation

Since, 8 green balls + 7 white balls = 15 balls

7 white balls + 5 red balls = 12 balls

And 8 green balls + 5 red balls = 13 balls

Now, if we pick 15 balls, they may be white, green or red but if we pick 16 balls, then its certain that there will be atleast one ball of each colour.

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