# College algebra

posted by .

The radioactive element has a half-life of about 28 years and sometimes contaminates the soil. After 47 years, what percentage of a sample of the elements remain?

• College algebra -

fraction remain = (1/2)^n where n is the number of half life

half life = p/n where p is the period of decaying i.e. 47 years

so, first find n (number of half life using the half life equation and then find the fraction remain. convert this fraction to %

hope that helps

## Similar Questions

1. ### Chemistry

Which radioactive sample would contain the greatest remaining mass of the radioactive isotope after 10 years?
2. ### calculus

The rate at which an amount of a radioactive substance decays is modeled by the differential equation dA/dt = kA, where A is the mass in grams, t is the time in years, and k is a constant. Answer the following. a) If a 100-gram sample …
3. ### College Algebra

The half-life of a radioactive material is about 34.6 years. How much of a 1-gram sample of the material is left after 30 years?
4. ### Science

What can scientists learn from the rate at which radioactive elements decay?
5. ### Pre-Calc

Tritium, a radioactive isotope of hydrogen, has a half-life of 12.4 years. Of an initial sample of 69 grams, how much will remain after 75 years?
6. ### College algerba

The​ half-life of a certain radioactive element is about 1500 years. After 2800 ​years, what percentage P of a sample of this element​ remains?
7. ### College algebra

If 70% of a radioactive element remains radioactive after 400 million years , then what percent remains radioactive after 600 million years?
8. ### Science

An element has a half-life of 30 years. If 1.0 mg of this element decays over a period of 90 years, how many mg of this element would remain?
9. ### math

An element has a half-life of 30 years. If 1.0 mg of this element decays over a period of 90 years, how many mg of this element would remain?
10. ### Math

The element strontium-90 is radioactive. The percent of strontium -90, A(t), left in a sample can be modelled by the half-life function A(t) = A0 (1/2)^t/29, where t represents the time, in years, after the initial time, and A0 represents …

More Similar Questions