### Epidemic Modelling

Use the computer to model an epidemic. Try out public health policies to control the spread of the epidemic, to minimise the number of sick days and deaths.

### Very Old Man

Is the age of this very old man statistically believable?

### bioNRICH

bioNRICH is the area of the stemNRICH site devoted to the mathematics underlying the study of the biological sciences, designed to help develop the mathematics required to get the most from your study of biology at A-level and university.

# Light Absorbance

##### Stage: 5 Challenge Level:

This question contains a lot of 'unused' information, so try to be clear as to which parts enter the calculation.

You might want to think through the problem in these steps:

First consider how the molar extinction coefficient relates to the absorbance of the initial solution in the light path cuvette using the Beer-Lambert law.

Then work out how a change in this absorbance relates to a change in the concentration. From this you can work out the change in the number of moles of chemical due to the sample of extract added to the cuvette.

Then you can scale up to determine the number of katals present in the original extract.