Results 1 to 3 of 3

Math Help - urgent optimisation - finding the maximum

  1. #1
    Newbie
    Joined
    Feb 2009
    Posts
    2

    urgent optimisation - finding the maximum

    Hi, I am stuck on part of the question:

    G(t) = -0.04t^3 + 0.9t^2 + 30 predicts your grade out of 100% on the next calculus test when you study t hours during the week before the test.

    How many hours of study required to achieve your maximum grade?

    Can someone please help me with this?

    I am able to differentiate but am unsure how to solve t. It doesn't fit into quadratic?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,829
    Thanks
    123
    Quote Originally Posted by kiwicraig31 View Post
    Hi, I am stuck on part of the question:

    G(t) = -0.04t^3 + 0.9t^2 + 30 predicts your grade out of 100% on the next calculus test when you study t hours during the week before the test.

    How many hours of study required to achieve your maximum grade?

    Can someone please help me with this?

    I am able to differentiate but am unsure how to solve t. It doesn't fit into quadratic?
    Use the first derivation:

    G'(t)=-0.12t^2+1.8t

    To get an extreme value G'(t)=0

    Solve this equation for t. You'll get t = 0 or t = 15

    Much to my surprise you'll get a grade of 30% if you don't study at all
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Feb 2009
    Posts
    2
    thanks very much, you have really saved my bacon!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding smallest dimension through optimisation
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: February 9th 2011, 03:07 AM
  2. Replies: 4
    Last Post: December 11th 2010, 04:32 AM
  3. finding the maximum...?
    Posted in the Calculus Forum
    Replies: 1
    Last Post: January 25th 2010, 11:01 AM
  4. Maximum profit - Calculus (urgent!)
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 31st 2008, 12:02 AM
  5. minimum and maximum URGENT!
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: August 14th 2007, 01:21 PM

Search Tags


/mathhelpforum @mathhelpforum