The correct answer is Choice B: 53.0 feet.
If you draw a picture of the cross section, you will have a right triangle. The hypotenuse is 58 and one of the legs is 23.6. All you have to do is use the Pythagorean Theorem and solve for the missing side.
x^2 + 23.6^2 = 58^2
Area = πr^2
π4^2 =16π
=50.3
Numerical, subtraction, s
So what you do first is find the area of this lawn and you do 10 by 12 and multiply those and you get 120 feet so now what you do is divived 120 by 3 and you get 40 so that means she mowed 40 ft in each hour so that would be the unit rate.