My students often panic and stop thinking when they encounter a question they don’t know how to solve.
We spend a lot of time talking about strategies they can use when they don’t know how to solve a problem directly: use a “ruler” or leverage what you DO know to find what you DON’T know.
Here’s a third method you can use when you don’t know how to solve a problem directly.
Eliminate wrong answers
This is from the ACT 2017-2018 Practice Test
Hmmm…can I draw a picture to represent the problem?
Looking at the pattern, I can see that the 7th space is going to be even. So I can immediately eliminate answers A and B.
Eliminate unlikely answers
What about answer C? Looking at the pattern, I can see that it’s too small for the 7th spot (It’s probably the correct answer for the 5th spot)
Guess between the rest
Even if I didn’t know how to or didn’t have time to solve it out any further, now I’ve got a 50:50 chance of getting it correct. The right answer is either D or E.
Doing some quick math in my head, I’d round -27 to 30 and multiply by 3 to get 90 – so the 5th spot will be a little under 90. 90 times 3 is 270 – so the 6th spot will be a little under 270. Rounding 270 to 300 and multiplying by 3 to gives me 900- so the 7th spot will be a under 900 – so E is the closest to my approximation.SAT/ACT tip: Sometimes you don't need to solve the question. You can just eliminate what doesn't work and make an educated guess among what is left. Click To Tweet
(And notice how fast that was – part of the trick of the SAT and ACT is not just finding the right answer, but finding the right answer QUICKLY so you have time to answer more questions.)