Question

A tile is drawn from a bag at random and then replaced. the probability of

drawing a blue tile is 80% and the probability of drawing a red tile is 20%.
what is the expected number of blue tiles in 25 draws?

Answer 1

The expected number of blue tiles is 20 blue tiles.

Explanation:

You can easily do 80% x 25 or

0.8 x 25 = 20

OR (other method)
Turn the 80% into a fraction
80 x
---- = -----
100 25

100 / 4 gives us 25, so 80 / 4 will give 20.

So the answer is 20 blue tiles.