I like Seth Godin (who doesn’t?) and I read his posts everyday. Today he tickled our minds with a simple math problem. Think about it…

Several people seem confused with the mathematics involved in his post:

http://sethgodin.typepad.com/seths_blog/2009/08/not-so-good-at-math.html

**Not so good at math**

A simple quiz for smart marketers:

Let’s say your goal is to reduce gasoline consumption.

And let’s say there are only two kinds of cars in the world. Half of them are Suburbans that get 10 miles to the gallon and half are Priuses that get 50.

If we assume that all the cars drive the same number of miles, which would be a better investment:

. Get new tires for all the Suburbans and increase their mileage a bit to 13 miles per gallon.

. Replace all the Priuses and rewire them to get 100 miles per gallon (**doubling** their average!)

Trick question aside, the answer is the first one. (In fact, it’s more than twice as good a move).

We’re not wired for arithmetic. It confuses us, stresses us out and more often than not, is used to deceive.

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**Actually it is very simple:**

The Suburban gets 100 miles for 10 gallons

The Prius gets 100 miles for only 2 gallons

With option A the Suburban gets 130 miles for 10 gallons or 100 miles for 7.69 gallons. A saving of 2.31 gallons per 100 miles

With option B The Prius gets 100 miles for only 1 gallon. A saving of 1 gallon per 100 miles.

Option A is 2.31 times better at reducing gasoline consumption.

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But please don’t get a Suburban! Don’t forget this assumes 50% of the people are using Suburban and 50% are using Prius. To reduce gasoline consumption it would be immensely better to get the Suburban drivers to switch to Prius each saving 8 gallons per 100 miles. This is 3 times better than Option A!

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*Related*

There is another problem with this question…

The assumption “If we assume that all the cars drive the same number of miles…” covers up an important fact: As anyone who has ever switched to a Prius knows, you do NOT drive the same number of miles when your car gets 50mpg as you do when it only gets 10mpg.

It’s the equivalent of saying that price has no effect on demand, but in reality it does. When the price of gas goes up, people drive less. And when the cost of driving goes down (as it does in Prius), people naturally drive more.

The average number of miles driven per year in a Prius is about 25K. In a Suburban it’s maybe 12K. Is that because people who need to drive more buy the more fuel efficient car? Or because those with more fuel-efficient cars drive more? Both.