Question

A bag contains 8 black marbles and 20 yellow marbles. You reach into the bag and pull out a black marble. Then you reach into the bag and pull out another marble. What is the probability that the second marble is yellow?

Answer 1

You have a bag containing 8 + 20 = 28 marbles.

After you pull a black marble you have 28 - 1 = 27 remaining marbles.

There are 20 yellow marbles in the bag.

The probability of pulling a yellow marble is now

$\frac{20}{27} which \: is \: approximately \: equal \: to \\ 74.07\%$