Question

A jar of marbles has 8 yellow, 3 red, and 9 green marbles. You select 1 marble, put it back, and then select another. What is the probability that you choose 2 red marbles? Express the probability as a fraction in simplest terms. Show your work.

What is the probability that you choose 2 red marbles?

Answer 1

Here total number of marbles is (8+3+9)=20

We are selecting marble with replacement here. That means for each drawing the time sample size is 20 .

There are 3 red marbles in the jar.

We want probability of 2 red marbles in 2 draws.

From 20 marbles 3 are red. So probability that the choosen marble is red in a draw is

Probability that in 1st draw the marble is red is   and again in 2nd draw probability that the marble is red is  

Then probability of choosing 2 red marbles is

= = 0.0225