Question

During the eclipse on January 26, 2009, the moon's shadow traveled 14,500 kilometers and covered 0.9 percent of the surface area of Earth. Earth's surface area is about 512 million square kilometers. Suppose the area covered by the shadow was rectangular. What would be the width of such a rectangle? Round your answer to the nearest kilometer.
A: 318km
B: 350km
C: 3178km
D: 392km

Answer 1

The area covered by the shadow is given by:
 A = (512,000,000) * (0.9 / 100)
 A = 4,608,000
 Then, since the area is a rectangle we have:
 A = (w) * (l)
 Where,
 w: width
 l: long
 Substituting we have:
 4,608,000 = (w) * (14,500)
 Clearing w we have:
 w = (4,608,000) / (14,500)
 w = 317.7931034
 Round to the nearest kilometer:
 w = 318 Km
 Answer:
 The width of such a rectangle would be:
 A: 318km