1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Word Problem

  1. Apr 8, 2009 #1
    1. The problem statement, all variables and given/known data
    The population of a country is growing exponentially. The population in millions was 120 in 1970 and 150 in 1980.

    (a) What is the population t years after 1970?

    (b) How long does it take the population to double?

    (c) When will the population be 400 million?

    2. Relevant equations

    3. The attempt at a solution
    I don't know how to start the equation, so I listed out the years and the populations to no avail.
  2. jcsd
  3. Apr 8, 2009 #2
    I'll give you the equation you need to use.

    P(t) = P0ekt

    P(0) = P0

    Use the information given in the problem to find your constant (k). Once you have that it is very easy.

    Cool, first post!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook