Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Improper Integrals

  1. Feb 15, 2009 #1
    1. The problem statement, all variables and given/known data
    Sales of the text Calculus and You have been declining continuously at a rate of 4% per year. Assuming that Calculus and You currently sells 4800 copies per year and that sales will continue this pattern of decline, calculate total future sales of the text.

    2. Relevant equations
    integral of a to infinity f(x)dx=lm of M>>infinity of integral of a to M f(x)dx

    3. The attempt at a solution

    I set the problem as integral of 0 to M 4800(0.96)^t dt and computed it, but my answer was incorrect. So then I did the opposite by setting the integral from M to 0, but my answer was still incorrect. Any help would be appreciated. Arigato Gozaimasu!
  2. jcsd
  3. Feb 15, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Your formula for 'declining continuously at a rate of 4% per year' is a bit wrong. Don't you want exp(-0.04*t)?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook