# Homework Help: Exponential Function?

1. Apr 18, 2009

### jackleyt

1. The problem statement, all variables and given/known data
Species A doubles every 2 hours and initially there are 6 grams. Species B doubles every 5 hours and initially there are 14 grams.

2. Relevant equations

3. The attempt at a solution
I've tried graphing this, but I don't think I have the right equations down. I don't know how to form the equations so I can solve the problem.

2. Apr 18, 2009

### whybother

In general for 'doubling time' problems, we have a simple formula

$$N = N_0 \times 2^{t \over T}$$

where N is the number of bacteria after t minutes and T is the time in minutes that it takes to double.

So if that's the relevant equation, attempting a solution should be possible.

EDIT: Although I don't actually know what your question is.

Last edited: Apr 18, 2009
3. Apr 18, 2009

### n!kofeyn

You didn't even say what the problem is.

4. Apr 18, 2009

### jackleyt

*How long until the species have the same mass? Sorry.

5. Apr 18, 2009

### whybother

Okay so you know the equations by which they grow for each of them, and then you set them equal to each other and solve for t.