Calculus homework help!!!

Hi Meredith. Pay attention in class from now on, thanks :P

PS I’m coming up to the room in like… an hour.

hi luv2mahsky,

This looks like a deriviative problem to me. I would find dm/dt first where m is mass of nicotine with respect to time (t)

Knowing that should answer b and c and a pathway to the rest of the problem. a good place for some info is mathforum.com

Hope it helps

If the half life is 2 hours, that means that in two hours you will have half of what you originally started with. You start with assuming a exponential decay relationship, i.e. Mass = Mass_original * e^(rt), where r is the rate constant. Because you know that when t = 2 the Mass left will be half of the original mass, regardless of how much you started with, (Mass_original / 2) = Mass_original * e^(2r). Solving the equation for r (see how Mass_original drops out?), r = (ln2)/2. You then have the exponential rate equation, m = m_o*e^(rt). This can also be expressed in the form m = m_0 * a^t, where a = e^r.

As for your four questions, once you have the equation they can be solved as follows.
1. plug in t = 1 and solve for m/m_o
2. plug in .4 for m_o and 24 for t (assuming instantaneous cigarette smoking at t = 0), solve for m.
3. plug in .4 for m_o and .08 for m, solve for t
4. solve general equation for m/m_o, plug in .2 for m/m_o, solve for t.

Hope this helps in time!

This seems a little like cheating to me. Am I off base here? Maybe it is because I didn’t have daily access to the internet when I took calculus.

This is exponential decay. Look it up.

No more help – that’s cheating!