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Bubbasch
I am facing difficulty with the CR specifically. I tried the pre-thinking and came up with the falsification scenarios. Negated them to come up with the assumptions. Checked whether those assumptions that I’d come up with as per my pre-thinking thought process are mentioned in the options or not. Surprisingly, none of them were there. No matter how many questions I solve with this approach, I couldn’t able to find any pre-thought assumptions (except for some easy, easy-medium arguments) which is frustrating. At first, I thought my approach of pre-thinking is incorrect, but it isn’t. Whatever the falsification scenario that I thought of was just one out of many. I build my assumptions based on only one and couldn’t find the one that I thought of. This kills my entire time as I wasted more than 2 mins apparently just to come up with an assumption based on pre-thinking which isn’t available in the answer choices. There’s no gurantee that the specific assumption will always be stated in the answer choices. There could be a million possible falsification scenarios and I cannot just sit and think every possible falsification scenario, negate them, and come up with an assumption and try to match them with the answer choices. This is the exact problem that even Charles from GMAT Ninja also mentioned in his first video of CR series and why pre-thinking doesn’t work all the time. However, many prep tutors are against this and always recommend pre-thinking. Charles suggests to identity the conclusion first and keep the premises in ready; start looking at each option and try to negate them and see if conclusion breaks 100% or not to find the correct answer choice. This approach strategically looks convincing and easy to adopt. However, I couldn’t execute this and cannot certainly cross out the wrong one out of the two deceitfully conceiving and closer answer choices. How should I be able to do overcome this dilemma and crack the code here? What’s your recommendation on pre-thinking? When I pre-think and that assumption is not there, it doesn’t mean that my pre-thinking is wrong. It’s just that my falsification scenario was out one of many. I don’t think any one can think of all the possible scenarios and try to come up with the assumptions and see if they match with the answer choices all the time. I did cross verify this with AI and it does agree with my argument. How do I overcome this and what should be the right approach to adopt to tackle every medium-hard, hard CR questions? Note that unless I solve the medium-hard, hard CR questions with right approach, I cannot be able to cross even V80.
I never prethink on any CR, I go by answer choice. The one thing that improved my CR in general was the understanding of the argument as a whole. I mean it may sound stupid, but at the end of the day, the mistake that we make is mostly because of some part of the argument which we didnt read as precisely as it should have been read. At the start, I had many assumption questions wrong, but as i started to read more carefully, it started to improve.
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Quote:

*chloreton writes:*
> I am facing difficulty with the CR specifically. I tried the pre-thinking and came up with the falsification scenarios. Negated them to come up with the assumptions. Checked whether those assumptions that I’d come up with as per my pre-thinking thought process are mentioned in the options or not. Surprisingly, none of them were there. No matter how many questions I solve with this approach, I couldn’t able to find any pre-thought assumptions (except for some easy, easy-medium arguments) which
I never prethink on any CR, I go by answer choice. The one thing that improved my CR in general was the understanding of the argument as a whole. I mean it may sound stupid, but at the end of the day, the mistake that we make is mostly because of some part of the argument which we didnt read as precisely as it should have been read. At the start, I had many assumption questions wrong, but as i started to read more carefully, it started to improve.
Did negating the answer choices work even for the hard questions? Especially, for the two most convincing options?
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Some didn't, some did. But i was able to spot and learn some pattern like scope change/something else(say C) didnt cause (say A) etc and that helps a lot along with negation.
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I agree with what’s said... everything boils down to how well you understand the argument. Personally, I break long sentences down part by part, connect the ideas, and focus on the logic. Spending about a minute on this has helped me choose answers faster without relying on the pre-thinking approach
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Thank you all for sharing your insights. Much appreciated :)
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Hi, could someone review this question and let me know if the way I solved it is right or not
[/url] https://gmatclub.com/forum/a-box-contai ... 33887.html

My solution is at the end. I used logic to check the probabilities but it felt a bit too straightforward and part of me is convinced I accidentally landed on the right answer. I'd appreciate the input of someone who is more experienced at this than I am : )

TIA
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while calculating the probability for unfair and fair, you have assumed the prob of picking fair coin to be 1/2 which is not correct since we dont know the number of fair or unfair coins , which is what we need to find.
Posted a solution
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The questions does say: "The probability that the coin was fair is exactly 1/2"

Am I misunderstanding this?

dp1234
while calculating the probability for unfair and fair, you have assumed the prob of picking fair coin to be 1/2 which is not correct since we dont know the number of fair or unfair coins , which is what we need to find.
Posted a solution
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Yes, there’s a subtle diff b/w both. Given you get one heads and one tails, probability of that coin being fair or unfair is 1/2. But the real ratio of fair and unfair coin is 8:9 which is what the question is asking. One trick to verify this is that you are getting an odd number of total coins in the end, can those be equally split?
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Yes i was also confused earlier at that point and got it wrong. But looking at the solution i concluded that the questions says that P( Heads from fair) and not P(Fair coins) is 1/2.
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Thank you, both of you responses were helpful : )
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Quote:

*Cyaa writes:*
Hi, could someone review this question and let me know if the way I solved it is right or not
a-box-contains-fair-coins-and-unfair-coins-when-one-of-the-unfair-coi-333887.html

My solution is at the end. I used logic to check the probabilities but it felt a bit too straightforward and part of me is convinced I accidentally landed on the right answer. I'd appreciate the input of someone who is more experienced at this than I am : )

TIA
Is the ans 17?
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Quote:

Is the ans 17?
Yea
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WA@ggs6090
Probably will get the access on the 22nd, as mentioned in the mail itself
The mail bb shared mentioned a month’s access on completion of the survey but I’ve only got 2 weeks. Anyone else received the same?
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The mail bb shared mentioned a month’s access on completion of the survey but I’ve only got 2 weeks. Anyone else received the same?
yes, me too. I think they changed the duration from 1 months to 2 weeks
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they should give for 1 month as promised
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I also received just 2 weeks, would have loved a month access, had planned things accordingly
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