Question 407377
the mean radius of the earth is 6,371 km, and 70.8% of its surface is covered by water.
 what is the surface area of the earth covered by land?
Surface area of sphere = {{{4*pi*r^2}}}
:
S.A. = {{{4*pi*6371^2}}}
S.A. = 510,064,472 sq/km total
:
Percent land: 100 - 70.8 = 29.2% land
therefore
.292 * 510064472 = 148,938,826 sq/km is land
:
:
if 167 cm squared of leather is stitched together to make a baseball, what is the radius of the baseball?
Using the Surface area of a sphere again
{{{4*pi*r^2}}} = 167
r^2 = {{{167/(4*pi)}}}
r^2 = 13.28943775
r = {{{sqrt(13.28943775)}}}
r = 3.645 inches is the radius of the baseball