SOLUTION: the level of thorium in a sample decreases by a factor of one-half every 2 million years. A meteorite is discovered to have only 8.6% of its original thorium remaining. How old i

Question 181467: the level of thorium in a sample decreases by a factor of one-half every 2 million years. A meteorite is discovered to have only 8.6% of its original thorium remaining. How old is the meteorite?
I am having a terrible time trying to figure out this question and I need to show my work. Can you please help me, Heather
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
the level of thorium in a sample decreases by a factor of one-half every 2 million years. A meteorite is discovered to have only 8.6% of its original thorium remaining. How old is the meteorite?
:
The half-life formula: A =
Where
A = final amt
Ao = initial amt
t = time years
h = half-life
:
In this problem, we assume the initial amt is 1 and final amt .086 (8.6%),
time and half-life in millions of years.
= A
= .086
we can ignore the 1
= .086
using logs here
= log(.086)
log equiv of exponents
*log(2) = log(.086)
Find the logs
.301* = -1.0655
Multiply both sides by 2
-.301t = -2.131
t =
t = 7.08 million years to decay to 8.6%
:
:
Check on a calc: enter: 2^(-7.08/2) = .086 ~ 8.6%
:
did this help you? any questions

RELATED QUESTIONS
The level of thorium in a sample decreases by a factor of one-half every 2 million years. (answered by stanbon)

The level of thorium in a sample decreases by a factor of one-half every 2 million years. (answered by ankor@dixie-net.com)

The level of thorium in a sample decreases by a factor of one-half every 4.2 million... (answered by ankor@dixie-net.com)

The level of thorium in a sample decreases by a factor of one-half every 4.2 million... (answered by scott8148)

The level of thorium in a sample decreases by a factor of one-half every 4.2 million... (answered by stanbon)

The level of thorium in a sample decreases by a factor of one half every 4.2 million... (answered by scott8148,gonzo)

you need to express the problem as an exponential function whose value is the percentage... (answered by stanbon)

5. The level of thorium in a sample decreases by a factor of one-half every 2 million... (answered by ankor@dixie-net.com)

Will you PLEASE HELP. I am clueless on how to work these problems. A cell divides... (answered by stanbon)