1. Not finding help here? Sign up for a free 30min 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!

Sequences and series

  1. Oct 8, 2006 #1
    I am not too sure what to do to answer this question.
    Each year for the past 5 years the population of a certain country has increased by a steady rate of 2.7% per annum. The present population is 15.2 million.
    a) what was thepopulation 1 yr ago?
    b) what was the population 5 years ago?

    I forgot what formula to use. Any help and reminders welcome. Thanks
     
  2. jcsd
  3. Oct 8, 2006 #2

    arildno

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Well, then re-develop that formula using your head (and our hints).
    You start out!:smile:
     
  4. Oct 8, 2006 #3
    I know the normal formula for compound interest is
    un = u1 * r^(n-1)
    so rearranging that would give u1 = ___(1.027)^5_____
    15.2 * 10^6
     
  5. Oct 8, 2006 #4
    then multiply that answer by (1.027)^(5-1)
     
  6. Oct 8, 2006 #5

    arildno

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Not sure what you are doing here. "1 year ago from n=1" is n-value n=0.
    Plug that into your equation.
     
  7. Oct 8, 2006 #6
    thanks I have already worked this out, sorry
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Sequences and series
  1. Sequences and Series (Replies: 1)

  2. Sequences and Series (Replies: 1)

  3. Sequences and Series (Replies: 9)

  4. Sequence and series (Replies: 1)

  5. Series sequences (Replies: 9)

Loading...