Algebra B (probability)
posted by Arika =] on .
I just don't understand how to do this...
A kidneyshaped swimming pool is located in a rectangular back yard. The sides of the pool consist of four connecting semicircles. A parachutist is hired to land in the back yard during a party. Assuming the parachutist lands in the back yard randomly, what is the probability that he will land on dray land ( not the pool)?
The back yard dimmensions: 30ft by 50 ft
large semicircle: 16ft
Two smaller semicircles: 8 ft ( both of them are )
Please help! I don't understand how! thank you!

If the parachute lands randomly inside the yard, the probability od landing in the pool equals the pool area divided by the total yard area (including pool)
The total yard area is 1500 sq. feet.
The total pool water area is 16 pi + 64 pi + (16x8). Draw the pool with connected semicircles with the large and small ones opposite each other in pairs) and you will see why. 
I assumed that the given semicircle dimensions were diameters. You didn't say. If they were radii, the pool is four times larger.
The probability of hitting dry land is 1  (Apool/Atotal)