Step-by-step explanation: 225 is the area and the formula for area is b*h (base times height) and from the problem, you can see that 18 inches is the height. In this case you would do 225/18 which gives you 12.5 sq inches.
Because in the theory of the outcome is a 50/50 chance landing heads or tails. So, the theorectical probability is 1/2. Now the experimental must be 11/20.