[sirinivas]

Box A contains 5 red and 3 white marbles and Box B contains 2 red and 6 white marbles.if a marble is drawn from each box,what is the probability that they are both of the same colour?

[Unknown008]

1. Draw a probability tree to help you.
2. When do you have marbles of the same colour?
- It's when you pick either 2 red marbles or 2 white marbles.
3. Use your probability tree to determine both, and add the two probabilities.

Post what you get! :)

[sirinivas]

can u explain it briefly
because,if we add probability of red and probability of white marles it is going to be 1.I think it should not be equal to universal set 1

[Unknown008]

Okay, here's the probability tree.



So, for you to get two marbles of the same colour, you need to have either 2 red marbles, or two green marbles!

The probability of having a red in Box A is 5 over 8 (there are 5 red and 8 marbles in all)

The probability of having a white in Box A is 3 over 8 (There are 3 white and 8 marbles in all)

The same logic is used for box B.

Now, when you you have the same marble colour? When you pick red THEN red, OR when you pick white THEN white.

The probability of having the same colour is the sum of the two possible events.

Follow the branch in the probability tree.

We get:



Can you complete it now? :)