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A bag contains six white beads, eight black beads and two green
beads. A lady draws beads out of the bag without looking at them and
without putting them back. What is the least number of beads that she must take out of the bag to ensure that she has taken out three beads of the same colour?
-- James.
I think she has to draw atleast four beads to ensure that she has taken out three beads of the same colour. Am I right with my answer!!!!!
Rajiv, Your answer is wrong but your approach is correct.
-- James.
I could get the solution.Can anyone post the answer and the approach for getting the same.
Its just trying your luck to get all three same colour.So the least number beads is three.
NO the answer is 7.
Since the bag contains beads of three different colour there is a possibility of not getting 3 beads of same colour till the 6th try.
Yeah, the correct answer is seven.
May be it is more clear if explained this way -
Let's suppose you are unlucky, and the first two consecutive draw yields two green beads. Now no more green beads available.
Now, for the next 4 consecutive draws, your draw yields 4 beads such that 2 are white and 2 are black (worst case scenario).
Your result at this point: six draws - 2 green, 2 white and 2 black.
The next draw (7th) will be either white or black, and consequently you will have one color repeated three times.
Thus 7 draws ensures that at least 3 are of same color.