Results 1 to 2 of 2

Math Help - Geometric Series 1

  1. #1
    Member
    Joined
    Feb 2013
    From
    Canada
    Posts
    131

    Post Geometric Series 1

    A tennis ball is dropped from a height of 20 m and bounces to 40% of its previous height on each bounce. The total vertical distance travelled is made up of the upward bounces and downward drops. What is the total vertical distance for the 6th time?

    My attempt:

    t1 = 20 cm
    r = 0.40
    n = 6

    Sn = t1r^n - 1 / r - 1

    S6 = 20(0.40^6 - 1) / 0.40 - 1

    S6 = -19.91808 / -.6

    S6 = 33.1968

    The correct answer is 46.6 m and I don't know how I can get that, any help would be appreciated!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,492
    Thanks
    1393

    Re: Geometric Series 1

    You've only counted the downward drops. You also need to count the upward bounces, which will be another geometric series with a = 8, r = 0.4 and n = 6.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: December 9th 2012, 12:50 PM
  2. Replies: 0
    Last Post: September 5th 2012, 11:21 PM
  3. Replies: 2
    Last Post: May 22nd 2012, 05:57 AM
  4. Replies: 3
    Last Post: September 29th 2010, 06:11 AM
  5. Geometric Progression or Geometric Series
    Posted in the Math Topics Forum
    Replies: 8
    Last Post: October 8th 2009, 07:31 AM

Search Tags


/mathhelpforum @mathhelpforum