Khan/khan-exercises — Issue #7077: Rate problems 1 - Question is backwards, suspect variable name mixup
Author: KhanBugz
Created: 2011-11-25 23:26:27+00:00
State: open
Labels: chrome, snowleo, wrong-or-unclear

http://www.khanacademy.org/exercise/rate_problems_1

Kevin traveled by motorcycle at an average speed of 17 miles per hour.

Then, he traveled by train at an average speed of 44 miles per hour.

In total, he traveled 160 miles for 5 hours.

How many miles did Kevin travel by train? (Round to the nearest mile.)

The answer it actually wants is the motorcycle distance. I think the nouns in the problem statement are backwards.

We can see that if we construct a coeffecient matrix and reduce it using RREF then multiply by the respective velocity we get the appropriate answers. Upon submitting the answer asked, it is marked incorrect, then after noticing the speeds were a bit silly I used the other one and it was correct.

[rate_problems_1.html?seed=38&problem=1](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/rate_problems_1.html?seed=38&problem=1&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/rate_problems_1.html?seed=38&problem=1&debug&activity=%5B%5D)

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