Comments on: [PS] Guitar Hero

By: Context: The Mathematical Cerberus | Irrational Cube

Context: The Mathematical Cerberus | Irrational Cube — Wed, 03 Nov 2010 05:08:43 +0000

[…] be anything else in the world? And who has a favorite orange anyways? Â Another example would be the guitar problem. Sure we can set up equations and solve to find the cost of a guitar, but this problem won’t […]

By: Chris Riesbeck

Chris Riesbeck — Wed, 20 Oct 2010 15:53:57 +0000

“A friend will sell you his Gibson for a fraction of the original cost. That fraction is 3/2. Should you buy it?”

By: Nicole

Nicole — Tue, 19 Oct 2010 16:24:26 +0000

I like Zeno’s suggestion, I’d just change the ending to “how much would you actually save over buying it new”.

By: ChadT

ChadT — Sun, 17 Oct 2010 19:36:40 +0000

My biggest beef with the original problem is the flippant use of the commutative property of addition. If the problem was written $30 less than instead of $30 more than, the $30 would come AFTER the subtraction sign. I am thinking in an Algebra I class, the commutative property would have been discussed by now? Ideally, put the $30 after the operation, be it addition OR subtraction.

By: Kristin

Kristin — Sun, 17 Oct 2010 14:55:41 +0000

LOL at Zeno’s question…you must hang out in the same guitar forums as my husband!

By: Chirs Sears

Chirs Sears — Sun, 17 Oct 2010 14:04:14 +0000

Zeno did do a good job cleaning up the problem. The only change I would make is the verb “told” in the second sentence. I think that “wrote” would be better because the transaction is taking place online. I know that this is picking nits.

By: Bowen

Bowen — Sun, 17 Oct 2010 05:38:35 +0000

Worse to me, here, is the process in setting up and solving the problem. What’s presented by the text suggests that a student can only solve the problem by “relating” in the specific way dictated above (eventually writing an equation). But what happens when the words change, or the order of the information changes? Lots of kids seem to botch this type of problem when they’d be fine if the cost of the original guitar were given and they were asked to find the cost of the model…

Nice job by Zeno of cleaning this up, and I shudder if kids end up thinking this is the type of work they might do at an actual music store.

By: Abby Noyce

Abby Noyce — Sat, 16 Oct 2010 20:27:11 +0000

The other real-life variant of this kind of problem is the small retail operation: “You bought widgets wholesale at $14.37 each. Your store’s standard retail mark-up is 150% above the wholesale price, and you want to round to the nearest $0.50 price point so you don’t have to deal with pennies. How much should you price each widget?” I did a lot of that math at various jobs…

By: Denise

Denise — Sat, 16 Oct 2010 19:46:27 +0000

I like Zeno’s version. It’s a reasonable application, and it also avoids the triple repetition of the awkward phrase “deluxe electric guitar.”

By: Dan Meyer

Dan Meyer — Sat, 16 Oct 2010 18:32:06 +0000

My word. That … almost does the job.