Question

Each cell divides to form two new cells every 30 minutes. If a culture starts out with exactly 100 bacterial cells how many bacteria will be present after 3 hours?

Answer 1

So, after 30 mins we have:

100*2

After 1 hour: 100*2*2, etc


the number of 2s will be the number of time they will divide: 3 hrs divided by 0.5 hour: this is six times.

So the final number of cells will be:

$100* 2^{6} =100 *2*2*2*2*2*2= 100 *8*8=100 *64=6400$


So after 3 hrs there will be 6400 cells there!