Friday

August 22, 2014

August 22, 2014

Posted by **Lee** on Sunday, November 8, 2009 at 7:47pm.

a) What is the half-life of the substance?

? years

(b) How long would it take the sample to decay to 10% of its original amount?

? years

- Calc -
**drwls**, Sunday, November 8, 2009 at 7:59pma) Let the half life in years be H

2^-(1/H) = 0.935

Solve that for H.

-1/H log 2 = log 0.935

-1/H = -0.09696

H = 10.31 years

b) Solve 2^-(t/10.31) = 0.10

t will be the time required to decasy to 10% activity

You could also solve

(0.935)^t = 0.1

The answer should be the same either way you do it: about 30 years.

- Calc -
**Lee**, Sunday, November 8, 2009 at 8:22pmThank you!

- Calc -
**Anonymous**, Friday, April 4, 2014 at 6:09pmhi

**Related Questions**

calculus - A sample of a radioactive substance decayed to 94.5% of its original ...

calculus - The rate at which an amount of a radioactive substance decays is ...

Science - Radioactive substance decays so that after t years, the amount ...

Math - A radioactive substance decays according to the formula Q(t) = Q0e−...

Math - A radioactive substance decays according to the formula Q(t) = Q0e−...

Calculus-derivatives - Verify if these are correct answers. 1. The derivative of...

calculus - Carbon-14 is a radioactive substance produced in the Earth's ...

Math/Calculus - After 5 days, a particular radioactive substance decays to 37% ...

precal - If the half-life of a certain radioactive substance is 2000 years, ...

Calculus - The half life of a certain radioactive substance is 10 years. How ...