Question

A bag contains 10 red marbles, 15 yellow marbles, 5 green marbles, and 20 blue marbles. Two marbles are drawn from the bag.

Which expression represents the probability that one of the marbles is red and the other is blue?

StartFraction 30 P 2 Over 50 P 2 EndFraction
StartFraction 30 C 2 Over 50 C 2 EndFraction
StartFraction (10 C 1) (20 C 1) Over 50 C 2 EndFraction
StartFraction (10 P 1) (20 P 1) Over 50 P 2 EndFraction

Answer 1

C

Explanation:

Answer 2

It is the third option: (10C1) (20C1( / 50C2.

Explanation:

The number of ways of selecting 2 marbles = the number of combination of any 2 marbles in the 50 marbles in the bag and this is 50C2. It is combinations because the order of drawing the marbles does not matter.

The number of combinations of one being red and the other blue = 10C1 times 20C1.

So the answer is (10C1) (20C1( / 50C2.