Another poorly written word problem (Part 5)

Textbooks have included the occasional awful problem ever since Pebbles Flintstone and Bamm-Bamm Rubble chiseled their homework on slate tablets while attending Bedrock Elementary. But even with the understanding that there have been children have been doing awful homework problems since the dawn of time (and long before the advent of the Common Core), this one is a doozy.

There’s no sense having a debate about standards for elementary mathematics if textbook publishers can’t construct sentences that can be understood by students (or their parents).

 

badproblem4

This one really annoys me. The area is less than 55 square inches, and so the appropriate inequality is

\frac{1}{2} (5)(2x+3) < 55

5(2x+3) < 110

2x + 3 < 22

2x < 19

x < 9.5

However, part (c) asks for the maximum height of the triangle. But there isn’t a maximum possible height. If the height was actually equal to 9.5 inches, then the area would be equal to 55 square inches, which is too big! Also, if any height less than 9.5 is chosen (for the sake of argument, say 9.499), then there is another acceptable height that’s larger (say 9.4995).

Technically, the problem should ask for the greatest upper bound (or supremum) of the height of the triangle, but that’s too much to expect of middle school or high school students learning algebra.

This problem could have been salvaged if it had stated that the area is less than or equal to 55 square inches. However, in its present form, part (c) of this problem is unforgivably awful.

Leave a comment

2 Comments

  1. It is just possible that the author thought that 54 was the “less than 55” number,
    This inequality thing has got completely out of hand.

    Reply
  1. Another Poorly Written Word Problem: Index | Mean Green Math

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