Question

There is a bag filled with 3 blue, 4 red and 5 green marbles.

A marble is taken at random from the bag, the colour is noted and then it is replaced.
Another marble is taken at random.
What is the probability of getting 2 the same colour?

would appreciate any help, ty :>

Answer 1

0.5

Explanation:

Total number of marbles = 10

Therefore, the probabilities of picking one marble:

P(blue) = 3/10 P(green) = 5/10 P(red) = 4/10

P(2 blues) = P(blue) AND P(blue) = 3/10 x 3/10 = 9/100 = 0.09

P(2 greens) = P(green) AND P(green) = 5/10 x 5/10 = 25/100 = 0.25

P(2 reds) = P(red) AND P(red) = 4/10 x 4/10 = 16/100 = 0.16

Probability of getting 2 blues OR 2 greens OR 2 reds = 0.09 + 0.25 + 0.16 = 0.5