# Math

Suppose a quantity is halvd every 18 years. use the approximate half-life formula to estimate its decay rate.

is the half life equation
y= 1/2^t1/2

2^1/2t= 1/y

t 1/2= log2 (1/y)

Where do I put 18 at?

1. 👍 0
2. 👎 0
3. 👁 197
1. quantity=originalamount*2-t/18
or as you prefer
quantity=originalamount*(1/2)t/18

1. 👍 0
2. 👎 0
2. Where do you get the original amount and the quantity from? I am confused since the problem doesnt have anymore numbers than 18

1. 👍 0
2. 👎 0
3. I really don't know what the question is asking, unless it wants the "decay rate"

quantity=oritinal amount(2t/18
take the ln of each side
ln(quantity)=ln(original)+t/18 * ln 2

now take the deravative...
1/q dq/dt=0+1/18 *ln2

so the decay rate is
dq/dt=q*ln2 / 18

1. 👍 0
2. 👎 0
4. What does dq stand for and dt? sorry for all the questions

1. 👍 0
2. 👎 0
5. dq/dt is rate of q changing with respect to time. It is a calulus term. dx/dt is rate of change of x, and so on. That is what surprised me about the question, rate is a calculus term.

1. 👍 0
2. 👎 0

## Similar Questions

1. ### math

Complete the table for the radioactive isotope. (Round your answer to two decimal places.) Isotope: 239Pu Half-life (years): 24,100 Initial Quantity: g Amount After 1000 Years: 0.6

2. ### Math

A radioactive substance decays according to the formula Q(t) = Q0e−kt where Q(t) denotes the amount of the substance present at time t (measured in years), Q0 denotes the amount of the substance present initially, and k (a

asked by Vanessa on April 6, 2014
3. ### Chemistry

Which radioactive sample would contain the greatest remaining mass of the radioactive isotope after 10 years? A. 2.0 grams of 198 Au B. 2.0 grams of 42 K C. 4.0 grams of 32 P D. 4.0 grams of 60 Co By the way the numbers next to

asked by Sanjay on March 3, 2007
4. ### Math

Skeletal remains had lost 84% of the C-14 they originally contained. Determine the approximate age of the bones. (Assume the half life of carbon-14 is 5730 years. Round your answer to the nearest whole number.)

asked by Vanessa on April 5, 2014
5. ### Calculus (math)

Warfarin is a drug used as an anticoagulant. After administration of the drug is stopped, the quantity remaining in a patient's body decreases at a rate proportional to the quantity remaining. Suppose that the half-life of

asked by luna on December 14, 2014
1. ### Gen Chem

Neptunium-239 has a half-life of 2.35 days. How many days must elapse for a sample of 239-Np to decay to 1.00% of its original quantity? I got: close to 15 days. Is this right? I figured that about 1% of the original quantity

asked by Sarah H on March 28, 2008

suppose m(0) milligrams of a drug are put in the blood of an injection. The amount of drug t hours after the injection is given by m(t)=m(o)e^-kt, for t (=>) 0, where k is the rate constant, which is related to the half life. we

asked by Jake on April 15, 2012
3. ### Math

the average life expectancy in canada is 80.1 years. Estimate the country's life expectancy in hours? I know the answer is 700,800 but I cant for the life of me figure out how they get that! Thanks

asked by Maggie on May 20, 2008
4. ### Math

A radioactive substance decays according to the formula Q(t) = Q0e−kt where Q(t) denotes the amount of the substance present at time t (measured in years), Q0 denotes the amount of the substance present initially, and k (a

asked by Vanessa on April 5, 2014
5. ### chemistry

If there are 80 milligrams of a radioactive element decays to 10 milligrams in 30 minutes then what is the elements half life in minutes? Ok i narrowed it down to either 10 or 30...but im rly confused so if u could help it wuld be

asked by jojo on March 4, 2007
6. ### calculus

Question: "Plutonium isotope Pu-239 has a half-life of 24,100 years. Suppose that 10 grams of Pu-239 was released in the Chernobyl nuclear accident. How long will it take for the 10 grams to decay to 1 gram?" I know that I am

asked by zak on February 26, 2009