Nice probability puzzle

For the last few weeks, Chris Maslanka's excellent maths puzzle column in the Guardian has been running variants on the following problem. Fred and Sam play a game in which the winner is the first to flip a head. They take it in turns, Fred starting. What's the chance that Fred wins? I have been asking this to 6th form audiences and the general response is 2/3 or 3/4, but nobody can say why. Here is the solution I have been using.

Mobile phones and behavioural problems

This article found an association between mobile phone use in pregnancy and behavioural problems in childhood, with an additional association with the child using a mobile phone before they were 7. I was not the only one reported as being sceptical, but the study is predictably getting a lot of coverage particularly in pregnancy advisory websites.

Do attractive people tend to have more daughters?

I got a commentary in the Times today (due to the Times paywall, this is a local link to the unedited article, rather than to the published version) about a study that estimated that people rated as 'unattractive' when they were 7 years old only had 44% chance of their first child being a girl. This effect seems utterly implausible.

Chance is a very fine thing

This month's Nrich has a fine collection of exercises on uncertainty, chance and coincidences, designed to be useful for primary schools to sixth forms. Have a look at the great lottery simulator, and try your hand at spinning 10 heads in a row like Derren Brown (there's a simulator if you get bored).

Lightning simulator

iconThis is really a quincunx made to look like lightning for a bit of fun. The lightning has to make 20 left or right choices on its way to the ground. If the stick man stays put he has a 1 in $2^{20}$ chance of being struck on each flash. That's roughly one micromort. As the strikes hit the ground the number of hits in each place appears as a bar chart.

The money's in the bag

Got an article in the Times about the Walkers Crisps forecasting competition. Since then have won another £10. Shame the paywall means there is no point in linking to the online version.

A sad day for molluscs

We are sorry to hear that Paul the ‘psychic’ octopus has died. Who would have predicted it? Most people, in fact, since an octopus is only expected to live 2 years. Fortunately a documentary film team got to Paul before his demise and conducted in-depth interviews. They also filmed me doing an explanation of the maths behind Paul – this will probably be cut but at least we now have an article about him!

Making money from the rain

I have just won £10 in the Walker's Crisps Rainy Day promotion. Each packet of crisps has a code that allows you to choose a 2km x 2km square in the UK or Republic of Ireland in which you think it will rain in a couple of days time. I won after only three entries at a crisp cost of £1.20, which seems quite a good deal.

Hang out the flags!

The great day has arrived. The first UN World Statistics Day, that is, which naturally falls on 20.10.2010. The bunting is out, and statisticians everywhere will emerge from their data-mines, blinking through their pebble spectacles. They will throw off their drab grey suits and dance in the street, discard the row of pens in their top pocket and trim their unruly hair, their dull monotone will turn to song and they will stop staring at their shoes.

Not sure about the weather? Now's your chance to show it.

We are working with the Met Office on a project comparing alternative ways of presenting uncertainty about short-term weather forecasts, and have a 6-month internship available for a PhD student. See this link for details.


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