500 ds

dunkin77 wrote:Hi,

I thought the answer was B) because there are black and red in Y after exchange, we can say no to the question "After the exchange, were both of the jelly beans in bowl X black?"

but the answer is E). can anyone please explain??

. Bowls X and Y each contained exactly 2 jelly beans, each of which was either red or black. One of the jelly beans in bowl X was exchanged with one of the jelly beans in bowl Y. After the exchange, were both of the jelly beans in bowl X black?
(1) Before the exchange, bowl X contained 2 black jelly beans.
(2) After the exchange, bowl Y contained 1 jelly bean of each color.

ok to know wether X has 2 black jelly beans after the exchange ... we need to know the color of the jelly beans bfor the exchange and the color of the jelly bean exchanged ... u already know that A is not the answer

for B consider the situation that both X & Y have a red and black jelly bean bfor the exchange ... and the black bean of X is exchjanged for the black bean of Y in which case Y wuld have 1 jelly bean of each color and so wuld X ..

now consider a second scenario .. X has 2 black beans and Y has 1 of each color ... and 1 black bean of X is excahnged for the black bean of Y ... in which case Y wuld have 1 of each color after the exchange and X wul have 2 black beans ...

looking at the 2 different scenarios ... the answer is E bcoz B does not give a defnite answer .... this is basically bcoz .. for knowing the color of beans after the exchange, we need to know the color of the bean bfor the exchange and the color of the exchanged bean, and neither of the statements gives us that information...

Okay - thank you!

For some reason I was under the impression that X, Y have two each and there are 2 red and 2 black in total.... but it dose not say anything about how many of which color in total....so E) must be correct.

Thanks