Question 2:
Another
substance has a halflife of 3 hours.
What fraction of the atoms will
have decayed after 6 hours?
Answer:
Threequarters of the atoms will have decayed
after 6 hours.
The halflife is 3 hours, so 6 hours
is 2 halflives.
After 2 halflives only one quarter
of the original atoms remain, which means that threequarters
of them have decayed. 

