Half-life is the time it takes for the radioactive material's mass to decrease by half.
So, half of 96 is 48
half of 48 is 24
half of 24 is 12
half of 12 is 6
96->48->24->12->6
You count how many arrows (->) there is.
Which is 4
Then you use the 12 minutes the question gave you to do:
12 divided by 4
= 3
So, one half-life (Or the time it takes for the radioactive material's mass to decrease in half) is 3 minutes
and every 3 minutes it will decrease by half.
