Tuesday, September 6, 2011

A lifetime of toilet roll

In the bathroom i began wondering, as you do, how many toilet rolls the average person uses in a life time. As i am a geek/weird i decided to work it out. By observation i have found that on average i use 1/3 of a roll a day. Over the course of a year this works out to 120.45 toilet rolls. According to official statistics the current life expectancy of a Briton is 80.1 years thus that works out at 9648.05 rolls in a lifetime.

Now obviously this contains a few assumptions. I've been using myself as a model but i am an average sort of bloke so its seems reasonable. Of course over a lifetime there are times you will use more and less toilet roll but we are talking averages here.

For a bit more fun i decided to see how far these toilet rolls would stretch if placed end to end. Measuring one of the rolls in my house i found the length of the tube to be 11cm. Thus 9648.05 rolls placed end to end would stretch for 1061.28m. This is a bit of a disappointment, just over a kilometre, i was hoping it would reach the Moon or something like that.

As a challenge my friend asked me how many double decker buses these toilet rolls would fill. An interesting challenge indeed, on the internet i found an advert for an exhibition double decker bus with an advertised floor space of 41m square. I thus calculated the available volume of a bus to be 82 cubic metres. This contains a few assumptions of course. For ease of calculation i used 2m for the height of the space on the 2 decks. This is more than it actually is but of course the floor space doesn't include the space for the driver and the stair well so you can add these. I think 82m cubed is a reasonable figure.

Now how much space does a toilet roll take up. Well of course a toilet roll is a cylinder but for our purposes we can assume it is a cube as when the rolls are placed side by side you can't fit anything in the space between. My model roll is, as i have already calculated 11cm long, and indeed it is 11cm wide too. Thus our roll is a cube with 11cm sides. Thus our roll has a volume of 1331 cubic centimetres which works out to 0.001331 cubic metres. A bus can therefore contain 61607.81 toilet rolls which means a single person's entire lifetime of toilet rolls can be easily stored on one double decker bus.  In fact 6.38 people could store their toilet rolls on a bus. So thats good to know.

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