Probability

grkmurthy · Senior Consultant Joined: 14 Oct 2007 Posts: 37

Lucy is having 7 quarters, 8 dimes and 6 nickels in her wallet.How many coins does she have draw in order to ensure that there is atleast 50 percent chance of drawing a nickel?

(1) 6
(2) 7
(3) 8
(4) 5
(5) 4

ksvickram · Senior Consultant Joined: 02 Jan 2008 Posts: 29

If the number of the nickel coins is atleast half the number if the quarters + dime combined together, then there is atleast 50% probability of picking up a nickel coin. So, for this to happen, one has to pick a minimum of 3 coins from quarters + dime , there is atleast 50% probability.

But I wonder no choice satisfies this. If anyone has a better solution, plz send across to me.