What’s the mistake? Why this mistake in particular?

Thanks again to Louise Wilson for the submission.

• Christopher

I got nothin’ on this one. I’m all ears.

• I don’t get it. The work looks like the work of someone who probably understands what’s going on, and then the answer chosen has nothing to do with the work at all?

• mr bombastic

They may be trying to do a dimensional analysis approach & multiplied all of those fractions together getting 11898.44 & figured 118.80 is the one that looks the most like their answer. I get all kinds of crazy stuff from students that set up long products of fractions hoping to convert from one unit to another.

• Leslie

Does the student have difficulty reading from one line to the next? Correct answer is d, but answer selected is c which is one line up.

• The student should write down the dimensions of each fraction. They should understand that the numerator and denominator of each fraction are equal, and so you’re multiplying by 1, and so it’s ok to flip the ratio. Then they should be asked what the units of the final answer, in this case dollars or better dollars/1. Then string the units together to cancel. Without the units it’s difficult to impossible for either the student or the teacher to follow along.