Fun with story problems

The best part of math for me was the story problems; you know the “If Johnny has six apples and you have no apples, and the government takes three apples from Johnny so it can give you one apple’s worth of applesauce while putting another apple in a “lockbox”, what happens to the remaining apple?”

Today’s Fixit column (it used to be “Mr. Fixit” before the surgery) took me back to those happy schoolboy days when a letter writer asked, “Does it burn more gas and so cost more money if you drive 75 miles per hour to get to a destination than if you drive 60 mph?” as opposed to ultimately saving money by getting there sooner.

Fixit offers this example in response:

Bob and Jim each need to drive 60 freeway miles from City A to City B. Both cars get 30 miles per gallon at 55 mph, the posted speed limit.

Bob travels at 55, but Jim speeds and does 75 mph — wanting to get there sooner.

At 75 mph, it would take Jim about 48 minutes to reach the destination.

At 55 mph, it takes Bob about 65 minutes to reach the destination.

At 55 mph, Bob used 2 gallons of gasoline. At $2.80 per gallon, that’s $5.60 to drive the distance.

At 75 mph, Jim would use 2.5 gallons of gasoline. At $2.80 per gallon, that would be $7 to go the same distance.

Fair enough. Jim pays an additional $1.40 to get to his destination 17 minutes sooner. Maybe it’s worth it to Jim to pay roughly the cost of a tall dark roast at Starbucks (no decaf for him, thank you) so that he can do something else with those 17 minutes of his life. Certainly the StarTribune columnist wouldn’t want to get into judging someone’s lifestyle choices, right?

However, it turns out that Jim paid $155.60 for this trip and arrived later than Bob.

How did this happen?

He was ticketed for speeding on the way and was fined (which could raise his insurance rates), and the stop slowed him down. (If they had traveled together in Bob’s car, both would have saved even more.)

Hmmm. Funny that it didn’t mention how much the boys would have saved (but not the taxpayers) if they had taken light rail. Or the bus. Or how much more time those options would have taken out of their lives. Funny, too, that speeding ticket scenario was gratuitously added in as Professor Fixit stepped from the chalkboard and up onto the soapbox.

In the same spirit, let’s assume that Jim, driving at 75 mph and closer to the prevailing speed of the rest of the traffic than Bob, doesn’t get a ticket and that he and Bob are competitors on their way to call on the same prospect. Jim gets there first, makes the sale and is on his way out to lunch with his new client by the time Bob is easing into a parking space. Or, let’s say Bob is really delayed because of the beat down he received from the long line of angry drivers that got stuck behind him, not to mention the related medical expenses that further drives up the cost of his trip.

Oh, but there’s more:

By the way, federal income tax credits of $250 to $3,400 are available in 2006 and 2007 to purchasers of hybrid-electric or diesel vehicles, based on the vehicle’s efficiency and fuel savings. (Tax credits are dollars deducted from taxes owed.) Act fast. After each auto manufacturer has sold 60,000 hybrids, the credit begins to phase out. See www.ase.org/taxcredits for details. (Check out local excise tax reductions and other benefits for hybrid purchasers, too.)

I don’t think Fixit read the article by Jamie Lincoln Kitman in the same newspaper, Best way to save gas may be to avoid hybrids, or this report: Hybrids Consume More Energy in Lifetime Than Chevrolet’s Tahoe SUV.

Numbers are fun!

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