Measurement and volume maths question

Question..
Dissolve the earth into little spheres so each person on earth gets their own sphere.
Find the radius, surface area and volume of each sphere.
The radius of earth is 6400km
There are 6930000000 people on earth
Help!

Hi,

If the radius of the earth is 6400 km, then its volume is 4/3πr³ = 4/3π(6400)³ = 1.098 x 10^12 km³

1.098 x 10^12 km
-------------------------- = 158.451 km³ for each individual's own little sphere
6930000000

158.451 = 4/3πr³

118.8383 = πr³

37.8274 = r³

r = 3.356878 km <==ANSWER for radius

SA = 4πr² = 4π(3.356878)² = 141.6058 km² <==ANSWER for surface area

V = 4/3πr³ = 4/3π(3.356878)³ = 158.451 km³ <==ANSWER for volume

I hope that helps!! :-)

Ok, deep breath.

I'm assuming that they are saying divide it by volume, so first we find out the volume of the earth (which is a sphere). Equation for the volume of a sphere is V=4/3 *pi* r^3

So plug in 6400km for r

This will give you the volume of the earth. Divide that number by the number of people. That will give you the volume of each "little earth."

Use the volume equation again, but this time you will solve for "r" instead of V. Now that you have the radius of the "little earth" you can solve the surface area of the "little earth" by using the formula for surface area of a sphere which is SA= 4 *pi* r^2

Good luck!