Browse · MATH
Printjmc
prealgebra senior
Problem
The figure shown represents a plot of land and is drawn using a scale in which 1 cm equals 2 miles. One square mile is 640 acres. How large is the actual plot of land, in acres? 
Solution
First, let's calculate the area of the plot of land in cm. Then, we'll convert as the questions ask.
Recall the formula for the area of a trapezoid is given by , so the area of this trapezoid is Now, we are given that . Squaring both sides, that means We are told that , so the above equation is actually:
Finally, we can convert
Recall the formula for the area of a trapezoid is given by , so the area of this trapezoid is Now, we are given that . Squaring both sides, that means We are told that , so the above equation is actually:
Finally, we can convert
Final answer
320000 \mbox{ acres}