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a
r = at + b where a and b are constants
1 = a(0) + b
2 = a(15) + b
b = 1
a = (1/15)
r = (1/15)t + 1
b
V = (4/3)(pi)(r^3) = (4/3)(pi)[(1/15)t + 1]^3
V(0) = (4/3)(pi)[(1/15)t + 1]^3 = (4/3)(pi)[(1/15)(0) + 1]^3 = (4/3)(pi)
V(t) = (4/3)(pi)[(1/15)t + 1]^3
(4/3)(pi) * 27 = (4/3)(pi)[(1/15)t + 1]^3
27 = [(1/15)t + 1]^3
3 = (1/15)t + 1
(1/15)t = 2
t = 30
At t = 30, the volume is 27 times larger than when t = 0.
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