Hi!
[spoiler]
IMO A[/spoiler]

this task is interesting:

A) P(white & even) = 0

P(white or even) = P(white) + P(even) - P(white & even)
there are only 5 white balls with odd number
P(white) = 5/25 = 1/5
we have 5 red balls and 5 blue balls with even number
P(even) = (5 + 5)/25 = 10/25 = 2/5
P(white or even) = 1/5 + 2/5 = 3/5
It is SUFFICIENT

B) P(white) - P(even) = 0,2

if there are more white balls than balls with equal number then some balls with equal number have the same number and the same color

we need more information about order

it is INSUFFICIENT

so I choose A

Maciek wrote:Hi!
[spoiler]
IMO A[/spoiler]

this task is interesting:

A) P(white & even) = 0

P(white or even) = P(white) + P(even) - P(white & even)
there are only 5 white balls with odd number
P(white) = 5/25 = 1/5
we have 5 red balls and 5 blue balls with even number
P(even) = (5 + 5)/25 = 10/25 = 2/5
P(white or even) = 1/5 + 2/5 = 3/5
It is SUFFICIENT

B) P(white) - P(even) = 0,2

if there are more white balls than balls with equal number then some balls with equal number have the same number and the same color

we need more information about order

it is INSUFFICIENT

so I choose A

How did you know there are 5 white balls? It never states exactly how many of each ball there are in the question.

you are right Makushr1 that it is not clearly defined.

we have 25 balls
each can be either red, blue or white
each of the balls has a number 1 to 10

red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
blue 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10
white 1, 2, 3, 4, 5, 6, 7, 8 ,9, 10

if probability(white&even) = 0 we can reduce number of above described balls by 5( 2, 4, 6, 8, 10)

thus we have 25 balls

red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
blue 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10
white 1, 3, 5, 7, 9

what would you choose and why?

Thanks Everyone! I have got it now.... The correct answer is E

@Pushkin...
can u pls tell me how much u got in quant when u gave d test??

@ Adi I got a 49 in quant and a 38 in English on my first attempt at GMatPrep 1

pushkin1982, why is the answer E?

Read The reply by Maciek

IMO (E)

25 balls = red, white, blue
each one has a number from 1 to 10

(1) there aren't any that are both white and even. This doesn't tell us how many are white or how many are even. insufficient.

(2) p of white - p of even = 0.2. this doesn't again tell you anything about the # of each. for ex. p of w = .5 and p of even = .3 which subtracted = .2 OR it could be any other combination that gives .2
so... insufficient ....Eliminate B.

Together:
Peven+white = 0. but there are still many posibilities for the other options just like as in statement (2).

Therefore (E).