lenny anf george started with 2 rabbits and each month the number of rabbits doubled since each pair of rabbits produced another pair of rabbits.

Question

what is an eqaution for this situation ?
Lenny and george now have 30 million rabbits. how many month have passed ?

Answer 1

Now = time(0) = 2 = 2^1
time(1) = 4 = 2^2
time(2) = 8 = 2^3
...
time(n) = 2^(n+1)

then 2^(n+1) = 10million
log both sides and use rules of logs

(n+1)log2 = log 10million
n+1 = log 10million/lon2 = 7/log2 = 23.25..
n = 22.25

after 23 months there will be more than 30 million