Question

the radiation from a sample of Krypton-85 decreases to one-third of the original intensity in a period of 18 years.What would be the intensity after 18 more years?

Answer 1

The law of radioactive decay tells us, that rate of decay is constant. That means, if for the rst 18 years the intensity decreases in three times, it will decrease again in three times after next 18 years. That is 9 times less from the original intensity.