Results 1 to 2 of 2

Math Help - exponential growth

  1. #1
    Newbie
    Joined
    Sep 2006
    Posts
    24

    exponential growth

    Tooth size reduction now has a rate of 1% per 1000yrs

    A) if t represents time in years and y represents tooth size, use the condition that y=yo.(99) when t=1000 to find the value of k in the equation y=yoe^kt. then use k in B

    so k=.00001

    B) in about how many years will human teeth be 90% of their present size?
    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 cyberdx16 View Post
    Tooth size reduction now has a rate of 1% per 1000yrs

    A) if t represents time in years and y represents tooth size, use the condition that y=yo.(99) when t=1000 to find the value of k in the equation y=yoe^kt. then use k in B

    so k=.00001

    B) in about how many years will human teeth be 90% of their present size?
    Hello,

    from 0.99 \cdot y_0=y_0 \cdot e^{k \cdot 1000} I got:

    k = - 0.00001005. I'll use this value for further calculations.

    to B) 0.90 \cdot y_0=y_0 \cdot e^{-0.00001005 \cdot t}

    First divide by y_0 and then solve for t:

    t=\frac{\ln(0.9)}{-0.00001005} \approx 10,483.6 \text{ yrs}

    That means: In round about 10500 years the teeth have only 90% of the initial size.

    EB
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Exponential Growth
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: October 25th 2009, 09:52 PM
  2. exponential growth
    Posted in the Pre-Calculus Forum
    Replies: 0
    Last Post: November 6th 2008, 07:37 PM
  3. Exponential Growth
    Posted in the Calculus Forum
    Replies: 3
    Last Post: October 1st 2008, 08:17 AM
  4. Exponential Growth
    Posted in the Business Math Forum
    Replies: 1
    Last Post: September 10th 2008, 02:54 PM
  5. exponential growth help
    Posted in the Calculus Forum
    Replies: 1
    Last Post: July 15th 2007, 04:16 PM

Search Tags


/mathhelpforum @mathhelpforum