# Question #74008

##### 1 Answer

Nov 2, 2017

#### Answer:

Another 15 years, for a total of 30...

#### Explanation:

...after 15 years, you have 50% of the original quantity. Half life is still 15 years, though, so after a further 15 years, half of the remaining quantity will disintegrate. Which is 50% of 50%, or 1/4 of the original quantity. Therefore, a total of 30 years.

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