Bunuel
Two plots, one square and the other, circular, were equal in areas. If the cost of fencing the square plot and the circular plot were $2 per feet and $3 per feet respectively, what was the ratio of the cost of fencing the square plot to that of the circular plot?
A. \(\sqrt{π} : 1\)
B. \(4\sqrt{π} : 3\)
C. \(4 : \sqrt{π}\)
D. \(3\sqrt{π} : 4\)
E. \(4 : 3 \sqrt{π}\)
Breaking Down the Info:We are given a relationship about the
areas. We can turn that into a relationship about the
lengths.
Set the length of the square as \(s\) and the radius of the circle as \(r\).
Since the areas are equal, we have \(s^2 = \pi *r^2\). We may square root this to get
\(s = \sqrt{\pi}*r\).
The cost of fencing is related to Perimeter * Cost Per Length (for the circle, that would be Circumference * Cost Per Length).
Then the ratio of the cost of fencing the square plot to that of the circular plot is:
\(\frac{\text{Perimeter of Sq} * 2 }{ \text{Circumf of Circle} * 3} = \frac{4s * 2 }{ 2 \pi r*3}\).
Now we may plug in the relation we found earlier, \(s = \sqrt{\pi}*r\), to get:
\(\frac{8*\sqrt{\pi}*r}{6 \pi r} = \frac{4}{3\sqrt{\pi}}\).
Answer: E