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Homework Help: Calculus Related Rates Interesting Problem

  1. Oct 25, 2009 #1
    1. The problem statement, all variables and given/known data

    http://www.kent.k12.wa.us/pcpow/questions/calc/0401trickortreat/index.html [Broken]

    This is an old problem, and I have been able to solve one and two, I believe the answers are

    1. pi cm/second
    2. 50(pi) cm^3/second
    3. This is the one I am not sure of. How can I solve this? Isn't there two many variables?

    2. Relevant equations

    dV/dt= 2(pi)r^2
    dC/dt= (2(pi))*cube root(V/(4/3(pi)))*(1/(4/3(pi)))*(dV/dt)

    3. The attempt at a solution

    I am getting lost at three, the rest are pretty easy, I think.

    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Oct 25, 2009 #2


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    Welcome to PF!

    Hi Gregarious101! Welcome to PF! :smile:

    (have a pi: π and try using the X2 tag just above the Reply box :wink:)
    Just do it the other way …

    The circumference is increasing at a rate of 1/8 cm per second: if it starts empty, what its it after five minutes?
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