# I must have missed this lecture

1. May 1, 2005

### monet A

I have a question here that I do not understand completely.
The Growth of virulent bacteria is modelled over a short period of time by a very ambitious mathematical modeller as n=
$$10^{10} (x sin2x + tan^4 x^7)^3$$
where x is measured in hours from x=.02 --> x= .1 from 12 noon.

The researcher observes that 1 minute and 12 seconds after noon n = 5 by three minutes after 12 noon n = ca 1250 and by 6 mins after noon the n = ca 78415. Show the model as proposed is a good fit for the numerical data. Determine the rate of Bacterial growth after 3 minutes.

I am not sure what I am being asked to do here. Am I just plugging in x values for the first half of the question or am I being asked to make a more complex analysis of the function between the said points. And for the second part of the question I presume that n (6) = 78415 is not a good fit for the function, but where shall I start to find a function that does fit, I am not sure of the method I should be employing here, I must have missed the lecture. Please help

Last edited: May 1, 2005
2. May 1, 2005

### OlderDan

The first part is just calculating the values for n at three values for x. They all fit reasonabley well. You do not need to look for a new function. What you need to do is use the given function to determine the RATE of change of n at 3 minutes. How do you find the rate of change of a function of time?

3. May 1, 2005

### monet A

That would be parametric differentiation yes?
Thankyou Dan for your help again.

4. May 2, 2005

### OlderDan

I'm not sure where you are seeing anything parametric. x is time and you have a function of x, n(x). The rate of change of the function with respect to time is the derivative with respect to x, dn/dx.