kitchen table math, the sequel: question

## Sunday, August 28, 2011

### question

From the October 2009 SAT:
There are 100 pieces of candy in a bag, 20 percent of which are wrapped. If a total of 70 percent of the pieces of candy in the bag are chocolate, what is the smallest number of wrapped chocolate pieces that could be in the bag?
The answer is 0, right?

C. had trouble with this problem, which led me to doubt my answer.

This brings me to an issue I've been meaning to raise.

Would this problem be easier if you worded it this way:
There are 100 pieces of candy in a bag, 20 percent of which are wrapped. If a total of 70 percent of the pieces of candy in the bag are chocolate, and the other 30 percent are caramel, what is the smallest number of wrapped chocolate pieces that could be in the bag?

#### 4 comments:

ChemProf said...

Right on both counts -- the answer is zero, and it would be easier worded the other way. This is a "left over" question, where a lot of the point is to figure out how much of the candy either isn't wrapped or isn't chocolate.

It is also a "put your calculator down!" problem -- since there are 100 pieces, you should never need to use it but a lot of modern high school students will start typing before they think. This slows them down, and as we've discussed, time is a big issue on the SAT.

Catherine Johnson said...

I've got to get Katharine on the case.

I haven't been able to work out in my mind the implicit rules of writing other than to know that I would write the sentence the second way, not the first.

I don't spell everything out for readers -- but I clearly have some kind of non-conscious rule about what has to be spelled out & what doesn't.

Katharine may know ---

Catherine Johnson said...

I find that a lot of the logic questions are purely about **not** inferring meaning in the way that you normally would.

The Venn diagram questions are especially bewildering to me because I would never write the way Venn diagram questions are written, and thus I don't read that way, either.

I would never say "30 students take geometry, and 25 students take Spanish" and leave the reader to understand that maybe some students take both and then again maybe they don't.

GoogleMaster said...

What was it you said once, something about you have to think like an autistic teenager, or read the question the way an autistic teenager would read it, or something like that?