### 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.

### Odd One Out

In this short problem, can you deduce the likely location of the odd ones out in six sets of random numbers?

Can you set the logic gates so that this machine can decide how many bulbs have been switched on?

# Light Absorbance

##### Age 16 to 18 Challenge Level:

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The molar extinction coefficient $\epsilon(\lambda)$ of a chemical measures theintrinsic property of how the chemical absorbs light of wavelength $\lambda$. When such light passes through a homogeneous solution of the chemical, the absorbance $A$ is measured by the Beer-Lambert law $A=\epsilon(\lambda) cL$, where $c$ is the concentration of the chemical and $L$ is the path length of the light passing through the solution. Recall that 1 katal = 1 mole per second.
With thanks to Keith Johnstone for providing the template for this question.