Tuesday, November 25, 2008

the problem with ..... legs!?

For my mathematically - able readers, here's something to exercise you prefrontal cortex on. The rest of you can use a calculator but I'd like to remind you to press the right button or you'll try to use that excuse for getting it wrong. ;-)

We thought that this problem would be a good brain teaser for students in our 9th grade classes.

Here it is:

There were seven girls on a bus and each girl had seven backpacks. Each backpack contained seven large cats and each large cats had seven smaller cats with them. How many legs are on the bus?

This is the original problem. The answer to this problem was used as a password for an EXCEL answer sheet file HERE.

Our problem has a little twist to it... we wanted to add the driver's legs as well! Also, to distinguish the math nerds from the math-nerds-wanna-be's we added an extension to it. After showing proficiency that students can answer the first part, as shown above, they now have to write an algebraic phrase or a general rule for n number of legs on the bus when n girls are present on the bus, provided the pattern follows, plus the bus driver's leg!

Goodluck, tfr!

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