Google’s Employment Applicant’s Hourglass Problem

Ref: March 2012 issue of Wired magazine.

It seems the Google job interview process requires a problem to be solved. I’ll take this hourglass problem, “Using only a four-minute hourglass and a seven-minute hourglass, measure exactly nine minutes.”

Solution Principle: Use one hourglass to measure out a smaller amount of time on the other hourglass. Repeat until you have the correct time periods stored in each hour glass such that when you add their times together by turning the second one up when the first finishes you get the correct total time of nine minutes. Continue reading “Google’s Employment Applicant’s Hourglass Problem”

Here’s A Little Brain Teaser


My mentor drAnalog has advised me how to use Google Analytics to produce statistics of site visits. The analysis has thrown up some interesting results and from them I have concocted a Brain Teaser for your delight. Sorry no prizes given but you have the satisfaction of taking part.

My Brain Teaser

  • Some Derby people made 21 visits to this blog using an unspecified number of computers which we have to assume kept the same settings for each visit they made and hopefully used the same service providers each time.
  • 13 visits were made using Internet Explorer, 6 using Google Chrome and 2 using Firefox browsers.
  • 16 visits were made with Windows PC’s and 5 with Mackintosh computers.
  • 18 visits were made via, 2 via and 1 via (service providers).
  • 18 visits were made using 24bit colour and 3 using 32 bit colour systems.
  • 8 visits used 1920×1200, 7 used 1366×768, 4 used 1280×800 and 2 used 1680×1050 screens.
  • 19 visits use Flash version 11.1 r102 with Java support and 2 use Flash version 10.0 r32 without Java support.

What was the minimum number of COMPUTERS needed to make the 21 visits to the blog?

I suspect there might be enough data to deduce the answer but I can’t guarantee it.

Answers posted in comments will be seen by others.