Question

The planet Mars could be a future destination for the U.S. space program. Assume that Mars is a perfect sphere. Its surface area is about 145 million square kilometers. What is the radius of Mars at its equator? Round to the hundreds place.
||| Answer choices:
A) 4,500 km
B) 2,200 km
C) 5,000 km
D) 3,400 km |||

Answer 1

Surface area of a sphere is  4 times pi timers radius^2
aprox pi=3.14

so surface area=145,000,000

145,000,000=4 times 3.14 times rdaius^2
145,000,000=12.56 times radius^2
divide both sdies by 12.56
11544585.987=r^2
square root both sides
3397.73=radius

round to the hundreds
3397 rounded to the hundreds
3400

the answer is D 3,4000 km