### Bistromath

I was standing with a dozen or so other people waiting for my coffee this morning as the woman behind the counter called out “regular latte”, “long black” and so forth. As I stood in my pre-caffeinated blur I hoped that no one else wanted a large capuccino because I couldn’t cope with fighting over whose it was. No one did. In fact, it hardly ever happens so I started thinking about the numbers.

There are about 15 different types of coffee/tea/hot chocolate on offer in various combinations. Some are only available in small size or only without milk and so forth so I am going to assume that for any different combination, two thirds of the previous set will apply. An arbitrary amount but probably not too far out. So I work it out like this:

Basic combinations | 15 |

times 1.6 for large/small | 24 |

times 1.6 for white/black | 38 |

times 1.6 for skim milk | 61 |

times 1.6 for soy milk | 98 |

times 1.6 for sugar | 157 |

This ignores people who ask for two or more sugars, or extra milk or some other combination I haven’t thought of. Then there are people who buy two or more coffees at the same time for which there is also no confusion.

I know the figures are a serious fudge. For instance, I think there might be a problem with the way I work out white/black/skim/soy but, even so, it is far more amazing that I have encountered a case of the same order than the reverse.

Just goes to show – we have a poor intuitive understanding of probability. Add to that in my case poor mathematical skills (see the above calculation) and no caffeine it is hardly surprising I got it wrong.

I need more coffee.

This entry was posted on Thursday, April 10th, 2008 at 1:38 pm and is filed under Science. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.