Why Leave Blanks on SAT?

kameronsmith
Tue, 24 Feb 2009 01:34:12 +0000

I always hear people saying that you should leave the question blank if you don’t know the answer. However, this doesn’t make much sense to me: you have more to gain than you have to lose.

For correct answers, you gain 1 point. For incorrect answers, you lose 1/4 point. For blank answers, your score stays the same.

Let’s assume you have 50 correct answers and have 10 questions you aren’t sure about.

If you leave all 10 blank, your score stays the same: 50.

Now, let’s imagine you guessed on all of them:
You have a 1/5 probability of getting it right. 10(1/5)= 2
You also have a 4/5 probably of getting it wrong, for which you lose 1/4 point. So 10(4/5)*(-1/4)=-2.

So, you would actually break even. Realistically, you could probably get most questions down to 3 potential answers. With this, your odds get even better.

10(1/3)=3 1/3
10(2/3)*(-1/4)=-1 2/3

So you’d net a total of 1 and 2/3 more points than if you had left the questions blank.

Is there something wrong with this math? What am I missing?