Answer :
Answer:
A
Explanation:
1 half-life = .4 kg = 15 years
2 half-life = .2 kg = 30 years
3 half-life = .1 kg = 45 years
4 half-life = .05 kg = 60 years
Answer:
A
Explanation:
Initial mass is 8. The half-life is 15 years.
1st half life=.8/2=.4
2nd half life=.4/2=.2
3rd half life=.2/2=.1
4th half life=.1/2=.05
For each half life that it took it to go from .8 to 0.05, you add 15 years since that is the half life of the substance. 4*15=60.
So, the answer is A. The material decayed from 0.8 kilograms to 0.05 kilogram in 60 years.