Question

There is a bag filled with 2 blue, 4 red and 3 green marbles.

A marble is taken at random from the bag, the colour is noted and then it is not replaced.
Another marble is taken at random.
What is the probability of getting 2 different colours?

Answer 1

.753

Explanation:

Let Ps = probability both marbles are the same color.

Let Pd = probability both marbles are a different color.

Pd = 1 -Ps

Let Pb = probability both marbles are blue

Let Pr = probability both marbles are red.

Let Pg = probability both marbles are green

Pb= 2/9 * 1/9 = 2/81

Pr= 4/9 * 3/9 = 12/81

Pg=.3/9 * 2/9= 6/81

Ps = Pb + Pr +Pg= 20/81

Pd =1-Ps= 61/81 = .753

Is this correct?