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Discussion in 'PCAT Discussions' started by kizoxef, Jul 22, 2011.
Honestly I go with my gut. If I change answers I'll most definitely get it wrong. If you pick an answer but tag it to come back to it, and still don't know the answer, leave it on what you first thought it could be.
Personally, I stick with my gut. In my experience, your gut is right many more times than it's wrong.
I also thought I'd add a couple guessing tips for folks looking for ways to help them narrow down answers. The Chem example below helped me on a few of the organic chem questions. And the Math example was a huge benefit to me.
Before leaving it up to a 25% chance, you should use a couple simple tricks to to improve the odds of you getting your guess correct.
99% of PCAT questions will contain some kind of clue to help you with the answer. Clues will sometimes be part of the question, or in the answers themselves. As long as you have a basic understanding of the sections, you should be able to spot these pretty quickly. If you're going into the PCAT with no study time and very few classes under your belt, then it's not so easy.
I'll pull an example from one of the practice tests I took:
CH3CHCH2 in a reaction with KMnO4 will yield which product:
a. CH3CH2CH3 + CO2
b.CH3CH2COOH + CO2
c.CH3CH2COO + CO2
d. CH3COOHCH2 +CO2
Without understanding how this reaction works, I can count the molecules involved in the reaction ( 3 C's, 6 H's, 4 O's) and know that answer A and C can't be correct because they contain 5 and 8 H's respectively. This narrows it down to 1 of 2 answers. At this point, I've already raised my odds to 50%. B and D are essentially the same answer, the only difference is on which Carbon the Carboxyl group forms, so at that point, you really need to know how the reaction operates. But just by counting molecules I've doubled my odds of getting the right answer.
Another great tip for math problems that are like "what is the value of x in ........" is to plug the answers into the equation until you find the right one. I've seen a lot of folks in tests like this stop at the question and try to solve from there. Rather than try to solve the equation, you know that 1 of the 4 answers presented is the correct one, save some time and use them!!
These two tricks helped me a lot with the Chem and Math section, but they're applicable across the board. The PCAT has a lot of tough questions, but it has a ton of hidden clues to find the answers - you just have to look for them.
Hope that helps, good luck!!
Going with your "first instinct" is a very popular myth.
Research shows that students who go back and change their answers are significantly more likely to raise their scores. I believe this is pretty well documented:
Even I have a hard time believing it but it makes sense if you think about it.
As for guessing, I suppose what the OP posted is about as far as you can go if you really know nothing about the question. However, like the guy above said, you can often find many hints in the question if you look carefully at your options.
Did you write this out correctly? CH3CHCH2 is 3 carbons whereas every choice has 4 carbons in the answer. I think the answer should be CH3COOH + CO2? Dunno if it's wise to try and match the number of atoms using KMnO4 unless the equation they give you is balanced because KMnO4 is usually in excess in these types of reaction.
Also I'm confused about to what extent should KMnO4 oxidize alkenes? I always thought KMnO4 oxidized alkenes into carboxylic acids and ketones:
But I just found this thing in which it only oxidizes alkenes into diols:
See, the clues are there if you look for them!
Good catch, I left out a C in the original.
Also, in response to your question if the double bond contains a primary C, it can cleave into a CO2 molecule. If the C's are secondary or tertiary as in your example, then they would cleave into ketones and carboxylic acids.
I'm having issues uploading a picture but a more accurate reaction example would be the permanganate oxidation of 3,7-dimethyloct 1-ene into 2,6-dimethylheptanoic acid + CO2
CH3CH(CH3)CH2CH2CH2CH(CH3)CHCH2 + KMnO4 ----->
CH3CH(CH3)CH2CH2CH2CH(CH2)COOH + CO2
Haha...I guess it's depends person to person, I just know from my experience. I think I ace a test and get it back, only to notice the ones I've thought twice about and changed last minute are wrong and my first gut answer was correct after all.
I believe it all depends on how you make that change and why. If you make that change because you overlooked facts or understood the question better after coming back to it, then in my opinion your second choice is your more educated one, thus the change is the correct answer. If you've narrowed it down to two and have no idea, but pick one anyway, I'd never go back and blindly select the other.
What if you actually got those questions right by changing your answer? You probably wouldn't remember it.
I believe it is something like 2/3rds of the time, a student who changes his/her answer ends up with a higher score.
Going from right to wrong feels worse than being wrong in the first place. Which may be why people are so hesitant to do it.
Furthermore, you're more likely to remember going from right to wrong than you are to remember going from wrong to right. If you got the question right, you probably won't think much of it. Do you really go over every single question you got right? Odds are, you mainly focus on the ones you got wrong.
I think it's something like 70 years of research that has been done on this. The data is pretty clear but people don't believe it lol (I'm still kind of on the fence too).
The only reason I know is because I'm one of those people who puts a mark beside each question I make an educated guess on or guess completely. I review each and every exam, so I'm pretty sure which one's I changed from right to wrong or vice versa.
Bottom line is people go against odds all the time and win, that's why I play the lottery! Just kidding...
Do what works for you!