Question

A hospital needs a circular landing pad for their helicopter. The landing pad should be 5000 square feet. The contractor calculated that the pad would need to be about 40 feet across. Formulas Is the contractor correct? If not, what error did the contractor make?

Yes, the answer is correct.
No, he forgot to multiply by pi (3.14).
No, he forgot to multiply the radius by 2.
No, he used the formula for circumference.

Answer 1

we know that
area of a circle=pi*r²-------> r=√[area/pi]
for area=5000 ft²
r=√[5000/pi]----> r=39.90 ft
39.90*2-----> 79.8 ft of diameter
79.8 ft is > 40 ft

therefore
the answer is
No, he forgot to multiply the radius by 2.