three chips are placed in an urn one is red on both sides a

three chips are placed in an urn. one is red on both sides, a second is blue on both sides, and the third is red on one side and blue on the other. One chip is elected at random and placed on a table. suppose that the color showing on that chip is red. what is the probability that the color underneath is also red?

Solution

three chips are placed in an urn. one is red on both sides, a second is blue on both sides, and the third is red on one side and blue on the other. One chip is elected at random and placed on a table. suppose that the color showing on that chip is red. what is the probability that the color underneath is also red?

There are 3 chips with 2 sides each:

When you draw a chip and place it with one face up, you actually have 6 possible results:

The question then removes all the possibilities where a BLUE face is showing, so the only possible results are the following faces:

Then the question asks what\'s on the other side of the chip, and these are the possible other sides of the chip:

So the chance that the other side of the chip is white, based on the fact that the face up chip is red, is 2/3.