Question

There is a bag a filled with 3 blue and 4 red 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 of the same colour?

Answer 1

• 3/7

Explanation:

Given

• Red = 4, Blue = 3

Total number of marbles is

• 3 + 4 = 7

Probability of getting 2 of the same color is

• P(2 same) = P(red, red) + P(blue, blue)

Probability of 2 reds is:

• P(red, red) = 4/7*3/6 = 2/7

Probability of 2 blues is:

• P(blue, blue) = 3/7*2/6 = 1/7

Required probability is

• P(2 same) = 2/7 + 1/7 = 3/7