Question

You pick two marbles from a bag with 5 blue marbles, 3 red marbles, and 2 green marbles. You pick the second marble without replacing the first one. Find each probability.

P(red then blue)
P(two blues)
P(green then yellow)

Answer 1

1/9

Explanation:

3 red

2 blue

5 green

Total

3

+

2

+

5

=10

Probability of blue is

2

10

~~~~~~~~~~~~~~~~~~~~~~~

Second condition:

3 red

1 blue

5 green

New total

3

+

1

+

5

=

9

Probability of green is

5

9

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Total probability of selecting this path is:

2

10

×

5

9

=

2

9

×

5

10

=

2

9

×

1

2

=

1

9