Monday

September 1, 2014

September 1, 2014

Posted by **Sam** on Tuesday, September 10, 2013 at 8:36pm.

amount is 133 grams. How long will it be until only 40 % remains?

- Math, science -
**Reiny**, Wednesday, September 11, 2013 at 7:38am1(1/2)^(t/12) = .4

2^(-t/12) = .4

take log of both sides

(-t/12) log 2= log .4

t = -12 log .4/log2 = appr. 15.9 years.

**Answer this Question**

**Related Questions**

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

calculus - assume the half-life of the substance is 31 days and the initial ...

math - assume the substance has a half-life of 11 years and the initial amount ...

Alegbra - Andrew measures the amount of a very unstable substance to be 100 ...

algebra - Andrew measures they amount of a very unstable substance to be 100 ...

Math - assume the substance has a half-life of 11 years and the initial amount ...

math - an extremely volatile substance, Ofnetite, has a half-life of 25 minutes...

math - if the rate for radioactive decay for a substance is r=-.0063 and time is...

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

Second order half life - At 100 degrees C , a certain substance undergoes second...