Question

5 blue and 9 red marbles are placed in a jar. Draw out 2 marbles without replacement. Find the probability that the last is blue.

Answer 1

5 blue and 9 red marbles are placed in jar . we draw out 2 marbles , without replacement , one by one.

to find the probability that the last is blue .

P(last is blue)

=P(last is blue and first is red)+P(last is blue and first is blue)

=P(last is blue given first is red)P(first is red)+P(last is blue given first is blue)P(first is blue)

now , P(first is red)

=9/14

P(last is blue given first red)

=5/13

P(first is blue)

=5/14

P(last is blue given first blue)

=4/13

so, required probability

=(4/13*5/14)+(5/13*9/14)

=0.357