Box

[jain2016]

A box contain 25 balls that are Blue, White, and Green. How many White balls are there?

1) There are fewer blue balls than green balls.

2) There are seven times more white balls that green balls.

OAC

Hi Experts ,

Please explain.

Many thanks in advance.

SJ

[GMATGuruNY]

The problem might be better worded as follows:

A box contain 25 balls. Each ball is blue, white or green, and the box contains at least one ball of each color. How many white balls does the box contain?

1) There are fewer blue balls than green balls.

2) There are seven times as many white balls as green balls.

Statement 1:
Case 1: b=1, g=2 and w=22, for a total of 25 balls.
Case 2: b=2, g=3 and w=20, for a total of 25 balls.
Since w can be different values, INSUFFICIENT.

Statement 2:
Case 3: g=1, w=7 and b=17, for a total of 25 balls.
Case 4: g=2, w=14 and b=9, for a total of 25 balls.
Since w can be different values, INSUFFICIENT.

Statements combined:
None of the cases above satisfies both statements.
Case 5: g=3, w=21 and b=1, for a total of 25 balls.
Case 6: g=4, w=28.
Since the total number of balls = 25, the values in Case 6 are too great.
Implication:
Only Case 5 will satisfy both statements.
In Case 5, w=21.
SUFFICIENT.

The correct answer is C.

[Brent@GMATPrepNow]

This question uses a common GMAT trap. It requires us to recognize that the number of balls of each color must be positive INTEGERS. If the question were written differently (say with 25 gallons of blue, white and green ice cream) then the values could be NON-INTEGERS (in which case, the answer would be E).

For more on this kind of trap (and others), see the following video: https://www.gmatprepnow.com/module/gmat ... video/1105

Cheers,
Brent