Question

Please help! A hat has the following marbles in it: 5 gray, 3 red, 6 white, 2 yellow and 4 green.

What is the probability of picking a gray marble, replacing the marble in the hat, and then picking a yellow marble?
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Answer 1

1/40

Explanation:

Probability: (number of ways to achieve the desired result / number of possible results)

For example, if we want a coin to land on heads:

We know there is one way for it to land on heads and two possible outcomes. Thus, the possibility of flipping a head is 1/2.

Using this, we know that there are 5 grey marbles (the desired result) and there are (5 + 3 + 6 + 2 + 4) total possible outcomes. The probability of drawing a grey marble is then:

5 / (5 + 3 + 6 + 2 + 4) =

5/20 =

1/4

We also know that there are 2 yellow marbles, so the probability of drawing one would be: 2 / 20 = 1/10

To find the probability of both of these events happening right after each other, multiply the probability of them each happening together.

1/4 * 1/10 = 1/40 chance of picking a grey marble and then a yellow marble.