Answer:
Percentage of the sample that would remain after the third half life is 12.5%
Step-by-step explanation:
After every half life, the amount of substance get reduced to it 50%
Let us say that initial amount of substance is 100
After 1 half life , remaining substance = 50
After 2 half life , remaining substance = 25
After 3 half life , remaining substance = 12.5
Percentage of the sample that would remain after the third half life is 12.5%