SOLUTION: Please help with: Suppose you have 500 grams of a radioactive element whose half-life is 72 years. a. Find the function for the quantity, Q left in T years. b. FInd to the

Question 331673: Please help with:
Suppose you have 500 grams of a radioactive element whose half-life is 72 years.
a. Find the function for the quantity, Q left in T years.
b. FInd to the nearest thenth of a year when there will be 100 grams left.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Suppose you have 500 grams of a radioactive element whose half-life is 72 years.
:
a. Find the function for the quantity, Q left in T years.
Q = 500*2^(-t/72)
:
b. FInd to the nearest tenth of a year when there will be 100 grams left.
Q = 100
500*2^(-t/72) = 100
Divide both sides by 500
2^(-t/72) =
2^(-t/72) = .2
Find the log of both side:
log(2^(t/72)) = log(.2)
log equiv of exponents
log(2) = log(.2)
=
using a calc:
= -2.322
t = -2.322 * -72
t = 167.2 years

RELATED QUESTIONS
Suppos you have 500 grams of a radioactive element whose half-life is 72 years. Find the (answered by ankor@dixie-net.com)

please help: Suppose you have 500 grams of a radioactive element whose half life is 72... (answered by nerdybill)

Hi I need help on my homework. Would you kindly please show me how to solve this problem. (answered by josgarithmetic)

A 1200 kg of a radioactive element kept decaying for 50 years until 300 kg of the element (answered by ankor@dixie-net.com)

You have just isolated a new radioactive element. If you can determine its half-life,... (answered by nerdybill)

At time = 0, there are 8000 grams of a radioactive material present. The half-life of the (answered by ikleyn)

The mass of a radioactive element at time x is given by the equation below, where c is... (answered by josgarithmetic)

The half-life of the radioactive element unobtanium-29 are initially present, how many... (answered by Alan3354)

Use Q(t)=Q sub 0 e^kt to solve: Find the half-life of a radioactive substance if 240... (answered by ewatrrr)