Volume ratio is 686/250 = 2.74
Area ratio is
250 yd^3
radii? First solid has vol 250 yd^3 = (4/3)*pi*r^3; find r^3 = --------------
(4/3)*pi
Then r^3 = 187.5 yd^3, and r = 5.724 yd
Second solid has vol 686 yd^3 .... Please find the radius R using precisely the same method.
Then calculate the ratio of the surface areas of the 2 solids:
Solid 1 surface area 4*pi* R^2
----------------------------- = --------------- where R is the radius of the larger
Solid 2 surface area 4*pi*r^2 solid and r is the radius of the smaller
R^2
This ratio comes out to ----------
r^2
Scale factor? Obviously one solid is larger than the other. We have to figure out by how much, by comparing volumes. Actually, we've already done that (see above). We could also determine how much larger R is than r. That, too, would give us the scale factor.