8th grade math
posted by Elizabeth .
Can you please check my answer?
A spherical balloon has a volume of 268 cubic cm. If more air is pumped in so that its radius is 3 times as long, what is its new volume?
My answer: 2,412 cubic cm

r^3 Becomes (3r)^3 = 27r^3,
New Volume = 27 * 268 = 7236 cc.
ALTERNATE METHOD:
V = (4/3)3.14*r^3 = 268 cc,
4.1888r^3 = 268,
r^3 = 268 / 4.1888 = 63.980,
r1 = 4.
New Radius = r2 = 3r1 = 3*4 = 12cm.
New Volume:
V = (4/3)3.14*(12)^3,
V = 4.1867 * 1728 = 7235 CC. 
6 negative 3

i need help