The yearly cost would be $138,000.
We will assume that this sample is typical of the shelter's usual numbers. We set up a proportion to estimate how many dogs yearly will have heart worm:
4/50 = x/5750
Cross multiply:
50*x = 4*5750
50x = 23000
Divide both sides by 50:
50x/50 = 23000/50
x = 460
We would expect 460 dogs per year to have heart worm. Multiplying this by the cost for each dog to be treated, we have
460*300 = 138,000.
