The micro-organisms double themselves in 3 hours. Assuming that the quantity increases at a rate…
The micro-organisms double themselves in 3 hours. Assuming that the quantity increases at a rate proportional to it self, then the number of times it multiplies themselves in 18 years is
32
64
128
40
Solution
Let initial number of microorganisms be $\mathrm{N}$. The microorganisms double themselves in 3 hours. $\therefore$ Number of microorganisms after
3 hours $=2 \times \mathrm{N}=2 \mathrm{~N}$
o hours $=2 \times 2 \mathrm{~N}=4 \mathrm{~N}$
9 hours $=2 \times 4 \mathrm{~N}=8 \mathrm{~N}$
12 hours $=2 \times 8 \mathrm{~N}=16 \mathrm{~N}$
15 hours $=2 \times 16 \mathrm{~N}=32 \mathrm{~N}$
18 hours $=2 \times 32 \mathrm{~N}=64 \mathrm{~N}$