A certain jar contains only b black marbles, w white marbles, and r red marbles. If one marble is to be chosen at random from the jar, is the probability that the marble chosen will be red greater than the probability that the marble chosen will be white?
(1) r/b+w > w/b+r
(2) b-w > r
Please Help...
thanks..
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- codesnooker
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Rephrase the DS question:
Is R>W?
Lets look at A
Is am assuming this r/b+w > w/b+r means r/(b+w) > w/(b+r )
r/(b+w) > w/(b+r )
rb+r^2>bw+w^2
rb-bw>w^2-r^2
b(r-w)>(w-r)(w+r)
if (r-w)>0 then b>(w-r)(w+r)/(r-w) or b>-(w+r)
if (r-w)<0 then b<(w-r)(w+r)/(r-w) or b<-(w+r)
A is insufficient
Lets look at B now
b-w>r
or b>r+w
B is insufficient
If we take both A and B then we know that r-w>0 or r>w and hence C is sufficient
Is R>W?
Lets look at A
Is am assuming this r/b+w > w/b+r means r/(b+w) > w/(b+r )
r/(b+w) > w/(b+r )
rb+r^2>bw+w^2
rb-bw>w^2-r^2
b(r-w)>(w-r)(w+r)
if (r-w)>0 then b>(w-r)(w+r)/(r-w) or b>-(w+r)
if (r-w)<0 then b<(w-r)(w+r)/(r-w) or b<-(w+r)
A is insufficient
Lets look at B now
b-w>r
or b>r+w
B is insufficient
If we take both A and B then we know that r-w>0 or r>w and hence C is sufficient
- codesnooker
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If condition 1 means: (r/b)+w > (w/b)+r then 100% (A) is alone sufficient, however if it means r/(b+w) > w/(b+r) then ans is (C).
Dferm, what is the correct question? I guess in future, at least you can take of to post the question in correct format.
Thanks
Dferm, what is the correct question? I guess in future, at least you can take of to post the question in correct format.
Thanks