Weekly Math Quest - Nov26th,2006

No takers?

The OA is B.

I will post the solution only if someone is interested.

solution?

[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.

thanks!

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