Knewton Weekly Quant Challenge - Week 1

by , Mar 17, 2010

We're happy to introduce the Knewton Weekly Math Challenge. Every Wednesday we'll post a very difficult quant question. The first person to answer correctly in the comment field below will win the new Knewton T-shirt. After the right answer appears in the comments (you can only post one answer, and you must explain how you arrived at your answer -- so take your time), we'll post a full explanation. Here's the first question. Good luck!

In a certain game, a player begins with a bag containing tiles numbered 1 through 10, each of which has an equal probability of being selected. The player draws one tile. If the tile is even, the player stops. If not, the player draws another tile without replacing the first. If this second tile is even, the player stops. If not, the player draws a third tilewithout replacing either of the first two tilesand then stops. What is the probability that at the conclusion of the game, the sum of the tiles that the player has drawn is odd?

A) 5/18

B) 13/36

C) 3/8

D) 5/8

E) 23/36