Results 1 to 5 of 5

Thread: [SOLVED] Sequence Question

  1. #1
    Member looi76's Avatar
    Joined
    Jan 2008
    Posts
    185
    Thanks
    1

    [SOLVED] Sequence Question

    Question:
    Each year a company gives a grant to a charity. The amount given each year increases by 5\% of its value in the preceding year. The grant in 2001 was \$5000. Find:

    (i) the grant given in 2011,
    (ii) the total amount of money given to the charity during the years 2001 to 2011 inclusive.


    Attempt:

    a = \$5000
    r = 5\% = 0.05

    2001 \rightarrow 2011 = 10 years

    U_{11} = a.r^{10}
    U_{11} = 5000 \times 0.05^{10} = 4.88^{-10}

    I don't think that is possible ! How can I solve this question?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Nov 2007
    Posts
    329
    Maybe r=1.05
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Moo
    Moo is offline
    A Cute Angle Moo's Avatar
    Joined
    Mar 2008
    From
    P(I'm here)=1/3, P(I'm there)=t+1/3
    Posts
    5,618
    Thanks
    6
    Hello,

    r is not 5%, but 1.05, because you keep the previous amount.
    Let's take an example :

    The first year, they give 5000$.
    The following year, they will give 5000 increased of 5%.
    This means that they will give 5000+5%*5000=5000+.05*5000=5000*1.05

    The following year, they will give 5000*1.05 added up by 5%.
    This means that they will give 5000*1.05+5%*(5000*1.05)=(5000*1.05)*1.05=5000*1.0 5

    Is it clear for you now ?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member looi76's Avatar
    Joined
    Jan 2008
    Posts
    185
    Thanks
    1
    Quote Originally Posted by looi76 View Post
    (ii) the total amount of money given to the charity during the years 2001 to 2011 inclusive.
    S_n = \frac{a(1 - r^n)}{1 - r}

    S_n = \frac{5000(1 - 1.05^{10})}{1 - 1.05}

    S_n = \$62889.46

    Where did I go wrong? Answer in text book is $71034
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Lord of certain Rings
    Isomorphism's Avatar
    Joined
    Dec 2007
    From
    IISc, Bangalore
    Posts
    1,465
    Thanks
    6
    Quote Originally Posted by looi76 View Post
    S_n = \frac{a(1 - r^n)}{1 - r}

    S_n = \frac{5000(1 - 1.05^{10})}{1 - 1.05}

    S_n = \$62889.46

    Where did I go wrong? Answer in text book is $71034
    Hi looi76,

    When the question says inclusive they mean both the year 2001 and 2011 should be included. So actually there are 11 years in all. So your n=11...

    S_{11} = \frac{5000(1 - 1.05^{11})}{1 - 1.05} = \$71033.93
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Monotone Sequence
    Posted in the Calculus Forum
    Replies: 3
    Last Post: Apr 19th 2010, 06:29 AM
  2. [SOLVED] Sequence problem
    Posted in the Calculus Forum
    Replies: 2
    Last Post: Mar 17th 2009, 07:53 PM
  3. [SOLVED] monotone sequence
    Posted in the Calculus Forum
    Replies: 1
    Last Post: Oct 11th 2008, 09:25 PM
  4. [SOLVED] sequence of agerages
    Posted in the Advanced Math Topics Forum
    Replies: 3
    Last Post: Sep 28th 2008, 02:21 PM
  5. [SOLVED] Fibonacci sequence
    Posted in the Advanced Math Topics Forum
    Replies: 1
    Last Post: Feb 23rd 2006, 12:01 PM

Search Tags


/mathhelpforum @mathhelpforum