This is the concept of exponential growth, the size of the colony after 16 days will be calculated as follows;
Exponential growth will be given by:
f(t)=ae^(kt)
where:
a=initial number=150
k=constant of proportionality=3/4=0.75
t=time=16
thus;
f(16)=150e^(0.75*16)
=24,413,218.71 bacteria