Here’s A Little Brain Teaser

Introduction

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 btcentralplus.com, 2 via ntl.com and 1 via virginmedia.com (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.