Tuesday, August 30, 2005

This Student May Keep His Calculator

As a homework problem, I posed the following questions to my students: You are selling remaindered hardcover books at the Delray Swap Shop in Delray Beach, FL (which I describe as "like eBay in person"), and you want the books to cost $5 after you have included Florida's 6% sales tax. What should be the base price of the book?

My student sends me the following email:

I know it is probably too late to ask for a little help on tomorrow's homework but I thought I would try anyway. On number 2 of the homework problems, I made a formula to solve the problem: Y= X+X(n) where Y=$5, n= 6%, and X= the base price of the book. I used my graphing calculator and found X to be $4.72. I checked the answer and everything worked out but when I tried to do the problem long hand it didn't.

On the good news/bad news front, it's nice that he used his calculator in an appropriate way to get an answer to a problem where the mechanics tripped him up. However, it's too bad that he needs to carry around an external brain in order to do algebra. (On the putting this in perspective front, sadly lots of students got this question VERY WRONG using methods undetermined.)