Here is a logistic growth formula:
L is the carrying capacity, given as 70.
a and b are constants to be determined from the given information.
The initial population, f(0), is 30:
The population increases by 50% each month, so the population after one month is 1.5(30)=45:
=-0.87547 to 5 decimal places
That function gives the following populations after n months to fill your chart:
months population (rounded)
-------------------------------
0 30 30
1 45 45
2 56.842 57
3 63.842 64
4 67.296 67
5 68.847 69
.
.
.
10 69.985 70