# Protactinium-234 has a half life of 1.17 minutes. How long does it take for a 10 mg sample to decay to 2 mg?

##### 1 Answer

Dec 6, 2015

#### Answer:

Solve

#### Explanation:

We need to solve

Taking logs of both sides:

#(t/1.17) log(1/2) = log(1/5)#

So:

#t/1.17 = (log(1/5))/(log(1/2)) = (-log(5))/(-log(2))#

So

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