Double Trouble!
A germ finds its way into your body at 4.00pm! Unfortunately, every minute it doubles into two germs. Luckily, you are on your way to an injection. However, its an hour before you reach. After half an hour, the germ population reaches 1073741824!
Finally, at 5.00pm you reach the doctor and get an injection. How many minutes prior to 5pm was the germ population 1/32 of what it was at 5.00pm?
The answer is 5.
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1 solution
This fact is the most important throughout:
.It doubles every minute.
The fact at half past the germ population was 1073741824 is useless. If you work it backwards you merrily do:
2 x 2= 4
2 x 2 x 2=8
2 x 2 x 2 x 2=16
2 x 2 x 2 x 2 x 2=32
Given there are 5 twos above, the point of which it was 1/32, was 5 minutes prior to the injection.