A cherry farm estimates from past records that if 23 trees are planted per acre, each tree will yield an average of 55 pounds o
f cherries per season. If for each additional tree planted per acre the average yield per tree is reduced by 1 pound, how many trees should be planted per acre to obtain the maximum yield per acre.?
This is a quadratic function that opens downward and has zeros at x=0 and x=78. The vertex (maximum) is on the line of symmetry, halfway between the zeros. The yield per acre will be a maximum when ...
x = (0 +78)/2 = 39 . . . . trees per acre
39 trees should be planted per acre to maximize yield per acre.