Sunday

January 25, 2015

January 25, 2015

Posted by **Melody** on Thursday, February 17, 2011 at 3:18pm.

The half-life of the radioactive isotope gallium-70 is 20 minutes. If the initial amount of gallium-70 is 25 milligrams, when will 10 milligrams be left?

- calculus -
**Reiny**, Thursday, February 17, 2011 at 5:36pmcan you solve

10 = 25(.5)^(t/20) where t will be in minutes ?

- calculus -
**Melody**, Thursday, February 17, 2011 at 5:48pmThis is what I got..

25(1/2)^(t/20)=10

(1/2)^(t/20)=10/25=2/5

(1/2)^(t/20)=2/5

t/20=log(2/5)/log(1/2)

t=20(log(2/5)/log(1/2))

t=26.44

Is this correct?

- calculus -
**Reiny**, Thursday, February 17, 2011 at 5:53pmcorrect, good job.

**Answer this Question**

**Related Questions**

math - How do I set-up/solve this problem? Please help me. The half-life of the ...

Chemistry - Gallium65, a radioactive isotope of gallium, decays by first order-...

chemistry - Gallium-67 is used medically in tumor-seeking agents. The half-life ...

chemistry - Gallium is a metal with a wide variety of uses. Some of its ...

math - What is the figure that gives the half-life of the isotope in minutes to ...

Half-life - After two hours, 1/16 of the initial amount of a radioactive isotope...

chemistry - If there are 80 milligrams of a radioactive element decays to 10 ...

Chem - There are two stable isotopes of Gallium Their masses are 68.92558 and 70...

Math - D.E.Q. - The half-life of a radioactive isotope is the amount of time it ...

College Algebra - Use a calculator to help solve the problem. One isotope of ...