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?

• 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.
• 9 years agoHelpfull: Yes(3) No(0)
• 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
• 9 years agoHelpfull: Yes(3) No(0)
• 20c3 means 17
• 7 years agoHelpfull: Yes(0) No(1)