This is an old brain teaser that someone told me, and which I shortened and clarified, as well as added clues for your students to use, as well as three different explanations for how to solve it.
Basically, the problem goes like this: you have 7 people who want to find the average of their salaries. The only problem is that no one wants to tell anyone how much they earn. How will you find the average without anybody stating their actual salary?
I've run this problem by all my techie type friends, and they're clueless. But you won't be, because I've included the solution and the mathematics behind it to help you!
Great for people who teach those allegedly "gifted students."
This problem will be included in the future release of "Statistics: 99.9% of you are teaching it wrong!", which I hope to have completed by the beginning of 2016. Like all my other "you're teaching it wrong" series, it will have lots of straight talk and snark, but ultimately transform you into an excellent teacher!