Exponential and Logarithmic functions

posted by .

A certain material decays at a rate of 1.9% per year. The sample is 260 grams. How much will be left in 11 years? How long will it take to have only a 100g sample left?

  • Exponential and Logarithmic functions -

    decay rate = 1.9% = .019

    amount of the 260 g left after 11 years
    = 260(.981)^11
    = ...

    b) when are left with 100 g ?

    260(.981)^n = 100
    .981^n = .384615...
    take log of both sides and use log rules:

    n log .981 = log .384615...

    continue

  • Exponential and Logarithmic functions -

    Thank you

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Chemistry

    It took 109.8 years for a 300.0 mg sample of an unknown radioactive material to completely disintegrate. Calculate the mass of the element (in grams/mole) assuming that the disintegrations per second are constant over the life-time …
  2. Math - Exponential Decay

    Radium decays exponentially. Its half-life is 1,690 years. How long will it take for a 50-gram sample of radium to be reduced to 5 grams?
  3. AP Calculus

    An Initial amount of 100 grams of Thorium-234 decays according to the model: dP/dt=-0.02828P (where t is measured in years). a) Find the equation for the amount of Thorium left after t years. b) Determine the half-life of this radioactive …
  4. Physics

    If a sample of a radioactive isotope has a half-life of 5 year(s), how much of the original sample will be left at the end of the second year?
  5. Calculus

    A certain radioactive material decays exponetially. The percent, P, of the material left after t years is given by P(t)= 100(1.2)^-t a)Determine the half life of the substance
  6. algebra

    Suppose a sample of Cesium-137 with initial mass of 200 grams decays to a mass of 160 grams voer the course of 10 years. Find the half-life of Cesium-137 (Round to the nearest year) How much Cesium-137 is left in the sample after 60 …
  7. 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 …
  8. 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?
  9. Pre Calculus

    If a 25 mg sample of radioactive material decays to 18.4 mg in 5 years, how long will it take the sample to decay to 20.5 mg?
  10. College algebra

    Sample of 500gms radioactive substance decays according to the function A(t)-500-0.044t where t is the time in years. How much of the substance will be left in the sample after 20 years?

More Similar Questions