Latest upsc Aptitude Question SOLUTION: A bag contains 20 balls. 8 balls are green, 7 are white and 5 are red. What is the minimum number of balls that must be picked up from the bag blind-folded (without replacing any o

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(#M40151895) UPSC General Ability question upsc Keep an EYE

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

Asked In upsc srisairam (9 years ago)

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lokesh  (9 years ago)

16 balls
[8(for green) + 7(for white) + 1(for red)]

let us suppose if we pick 3 balls , these MAYBE one of each color but not Surely.

BUT if we pick 16 ball , even in the worst case we will get one ball of each colour.
worst case refers to getting 8 green balls in the first 8 picks and then getting 7 whites in next seven picks.On the 16th attempt
we will get red ball only.

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Siva  (8 years ago)

16,if we consider worst case of picking balls first we pick 8green balls and next 7white balls upto this there are 15 balls are picked then if we pick a ball from bag that must be the red then we get the balls of at least one color each,finally the no of balls picked is 16

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RAHUL AMBAR YETRE  (6 years ago)

20c3 means 17

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