Weekly Math Quest - Nov26th,2006

gmat_enthus · Posted: Tue Dec 05, 2006 4:47 am Post subject: Weekly Math Quest - Nov26th,2006

Q. A box contains identical balls in three different colors - Black, white and blue. There are 8-x blue balls and 2X+5 black balls. If a ball is picked at random from the box, what is the probablity that the ball is either blue or black?
1) X=2
2) There are 3X+39 white balls in the box.

The answer will be posted along with the solution on Sunday, Dec 10th, 2006. Till then you can disucss your solutions here.

Reference: www.scorechase.com

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gmat_enthus · Posted: Thu Dec 07, 2006 10:22 am Post subject:

No takers?

gmat_enthus · Posted: Tue Dec 12, 2006 6:04 am Post subject:

The OA is B.

I will post the solution only if someone is interested.

tenpercenter76 · Posted: Wed Dec 13, 2006 10:30 am Post subject:

solution?

gmat_enthus · Posted: Wed Dec 13, 2006 10:44 am Post subject:

[copying what was posted by guardian on Scorechase]

Q. A box contains identical balls in three different colors - Black, white and blue. There are 8-x blue balls and 2X+5 black balls. If a ball is picked at random from the box, what is the probablity that the ball is either blue or black?
1) X=2
2) There are 3X+39 white balls in the box.

1] X=2, clearly insufficient

2] Total balls = 3x+39 + 8-x + 2X+5 = 4x + 52 = 4[x+13]

Probablity of getting either a blue or a black ball = [8-x + 2x + 5] / 4[x+13]
= [x+13]/4[x+13] = 1/4. Suff condition

Choice B.

tenpercenter76 · Posted: Thu Dec 14, 2006 8:56 pm Post subject:

thanks!

for some reason i though thought 8-x was simply 8x.