Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
A certain jar contains only b black marbles, w white marbles [#permalink]
04 Apr 2007, 16:47
0% (00:00) correct
0% (00:00) wrong based on 0 sessions
HideShow timer Statistics
This topic is locked. If you want to discuss this question please re-post it in the respective forum.
A certain jar contains only b black marbles, w white marbles and r red marbles. If a marble is picked at random from the jar, is the probability that the marble chosen be red greater than the probability that the marble chosen will be white?
Answer is A
Probability of choosing red marble = r/(b+w+r)
Probability of choosing white marble = w/(b+w+r)
To compare these two probabilities, we should know the relation between r and w
Lets consider the statement 1:
r/(b+w) > w/(b+r)
r(b+r) > (b+w)w
rb+r^2 -bw_w^2 > 0
b(r-w) + r^2 -w^2 > 0
b(r-w) + (r+w)(r-w) > 0
(r-w)(b+r+w) > 0
as we know b+r+w will always be positive
so r-w> 0
r > w
hence we can say the prob of choosing red marble is greater. SUFF
Statement2 : does not establish any relation between r and w. INSUFF