I just sent a puzzler idea to Car Talk and since they probably won't use it (too simple, perhaps?) I thought I'd give you guys a crack at it. No, I don't mean that I think you guys are simple minded... It's just a fun little mind-teaser.

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Yesterday I drove my new car, a Honda Fit, from San Jose to Reno and back, a round-trip distance of 500 miles. On the outbound leg, according to the mileage gauge I got 43.5 MPG. I didn't reset the gauge for the return trip, and when I arrived home the gauge showed an average for the entire trip of 46.5 MPG. The difference between outbound and return trip is because it is mostly uphill going out, downhill coming back. (Reno is a mile higher than San Jose)

So here's the question. If I got 43.5 MPG on the way out and 46.5 overall, what was my MPG on the return leg?
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Try and work it out before you look at the spoiler. It is not difficult math, but you do need to know how to approach the problem.



These are real numbers by the way - I really did make the trip, and with two traverses over Donner Pass (elevation ~7300 feet) 46.5 MPG average is respectable. Speed (cruise control) was 60 MPH with occasional bursts to 70 or 75 passing trucks (I needed to get out of the passing lane quickly to avoid 11 MPG SUVs that wanted to pass me), and occasional periods of 0--10 MPH in traffic jams. Overall average speed for time spent on the road was 59 MPH. (9.5 hours door to door with an hour of down-time in Reno. Purpose of trip was to pick up an Ekornes recliner chair purchased on eBay.)

tanstaafl.