Home > Math Lint Archive Detail

 << Prev 5/3/2009 Next >>

## Textbook Error

Some time ago, I asked readers to submit examples of where/when math texts make errors. Unfortunately, only one response was sent, which must mean that few errors are present...right?

A.O. (Evergreen, WA) sent the following: The text is 1992 Merrill Algebra 2, lesson on quadratic functions, p.325 #33 (a fairly good text, by the way).

S = ViT + 1/2 AT2 is introduced in an example about acceleration and its effect on distance. Then a little sidebar next to problem #33 says that "deceleration would be a negative number" in the same formula.

Here, then, is problem #33. Juanita is driving a truck at an initial velocity of 60 ft/sec. She sees a stop sign 240 ft. ahead of her. If she begins to decelerate at a rate of 3 ft/sec2, how long will it take her before she STOPS at the stop sign?

The book itself says that the answer is "35.5 seconds."

Ah, yes, stopping. Minor detail. The people who wrote and edited the problem perhaps did not consider matching the distance to the stop sign with the given rates. Oopsie.

....Math is such fun! A.