Try this problem from I.S.I. B.Stat TOMATO Objective Problem based on Box and ball Probability.
A box contains 100 balls of different colours 28 red 17 blue 21 green 10 white 12 yellow 12 black. The smallest number n such that any n balls drawn from the box will contain at least 15 balls of the same colour is
number Series
Logic
Integers
Answer: 77
B.Stat Objective Problem
Challenges and Thrills of Pre-College Mathematics by University Press
28 -15 gives 13 and 17-15 gives 2 and 21 -15 gives 6 rest are less than 15
then 100 -13=77 and 100-2=98 and 100-6= 94
then smallest number= 77
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