Posted by alejandro on Tuesday, July 3, 2012 at 4:16am.
The mass of a radioactive sample is represented in the graph below. The initial mass of 32 mg decays to 8 mg after 21 hours.
1)What is the half-life of the radioactive sample, in minutes?
2)Solve each equation.
a. 4 8x-1 = 8
b. 3^(2x-5) = 1/27x
- math30 - Steve, Tuesday, July 3, 2012 at 5:17am
8 is 1/4 of 32, so two half-lives = 21 hours.
half-life is 10.5 hours
4^(8x-1) = (2^2)^(8x-1) = 2^(16x-2) = 8 = 2^3
so, 16x-2 = 3
x = 5/16
assuming 1/27x = (1/27)*x,
3^(2x-5) = (3^-3)x
(2x-5)log3 = -3log3 + logx
(2x-2)log3 = logx
assuming a typo, and the x on the right does not belong,
3^(2x-5) = 1/27 = 3^-3, so
2x-5 = -3
x = 1
Answer This Question
More Related Questions
- calculus - The rate at which an amount of a radioactive substance decays is ...
- physics - Suppose 32000 radioactive nuclei are in a sample. About how many ...
- Physics (Inside the atom) - A sample of radioactive isotope I is to be used for ...
- math - An unknown radioactive element decays into non-radioactive substances. In...
- Calculus-Modeling Equations - An unknown radioactive element decays into non-...
- Chemistry - Which radioactive sample would contain the greatest remaining mass ...
- MATH! - The mass of a radioactive substance follows an exponential decay model, ...
- Physcis 30 - Q1) If there are 100 radioactive atoms with a half-life of 30 ...
- physics - The half-life of a certain radioactive isotope is 32 hours.What ...
- Chemistry - As a sample of the radioactive isotope 131 I decays, its half-life a...