To resolve this problem you need the following equation for exponential growth: [tex]N(t) = N_{0} e^{rt} [/tex].
The N(t) represents the size of the population in a concrete moment of time (t), the N_{0} is the initial size of the population and the rt refers to the rate of growth of said population. Baring this in mind, here are the answers:
a) N(9) = 70 × 2³ = 560
b)
N(t) = 70 × 2^{t/3}
So let's say the number of bacteria is 120000
1200000 = 70 × 22^{t/3}
1200000 ÷ 70 = 22^{t/3}
17142.9 = 22^{t/3}
log_2 17142.8 = log_2 22^{t/3}
14.07 = t/3
t = 14.07×3
t = 42.21
c) N(16) = 70 × 2^{16/3} = 1529173.3333333333333333 = 1529173
