### Inspector Morse

You may like to read the article on Morse code before attempting this question. Morse's letter analysis was done over 150 years ago, so might there be a better allocation of symbols today?

### Warmsnug Double Glazing

How have "Warmsnug" arrived at the prices shown on their windows? Which window has been given an incorrect price?

### Substitution Cipher

Find the frequency distribution for ordinary English, and use it to help you crack the code.

# Reaction Timer

##### Stage: 3 Challenge Level:

In this problem, you will meet two different ways to test your reactions.

This reaction timer will enable you to collect data on the time it takes you to respond to an image on your computer.

This text is usually replaced by the Flash movie.

Note: You can right click (or control-click if your mouse has only one button) on the 'Times' panel to select, clear or copy the times. This allows you to paste them into a spreadsheet or text document.

Here is a second experiment you can use to test your reactions.
Ask a friend to hold a ruler by the end, above your hand. Open your hand below the ruler and be ready to catch it. Your friend will drop the ruler without saying when they're going to let go. Catch the ruler as fast as you can after it's been dropped.
The pictures below show this experiment being carried out:

Record the level (in centimetres) at which you caught the ruler, and repeat the experiment several times. If you have quick reactions, the ruler will not have travelled far when you catch it.

Taking only one measurement in either of these experiments will not give you a reliable, accurate measure of speeds of reaction that could be used to rank a group of people.

Decide how many measurements you will take, and what you will do with them to provide an accurate measure of reaction speeds. Make sure you can justify your decisions.

#### Here are some questions you might like to consider:

• I think I respond more quickly with my right hand than with my left - are you the same?
• Do your reactions vary depending on the time of day or the sort of thing you are being asked to react to?
• Do your reactions improve with training/practice?
• Do boys react more quickly than girls?
• Do young people react more quickly than older people?
• What else do you think affects people's reaction times?
• Are both experiments testing the same ability? If you perform both experiments with a group of people and rank them in order, will the rankings be the same for both experiments?
• Can you think of other experiments you could do to test your reactions?
Test any hypotheses you come up with, and send us your analysis and conclusions.