[720 Q49 V40] My Blog: Errors and lessons learned

mayonnai5e · Posted: Fri Sep 14, 2007 4:03 pm Post subject:

My general CR strategy:

I read the stimulus the first time around fairly quickly then summarize the stimulus in my mind and look at the answers. I eliminate the obvious incorrect choices and if there are 2 or more choices left, I go back to the stimulus and reread again, paying particular attention to small details like adjectives and other "qualifying" words.

For some easier CR questions, the answer will leap out at you so don't waste time super analyzing the stimulus before reading answer choices. Get a general idea then try to find the answer. This saves time in the long run. If, however, the answer is not immediately apparent, go back and look for the tiniest details because the subtle details often are the key to eliminating the remaining incorrect answer choices.

mayonnai5e · Posted: Fri Sep 14, 2007 5:59 pm Post subject:

Man, doing 30 timed, CRs in a row is exhausting. It doesn't help that it's 2:30 AM here in Paris either. But at least I've completed the CR section of the OG11 book. For the entire section, my hit rate was 89%. That's not as good as I had hoped, but I have to keep in mind that most of my progress made in CR actually came from doing these problems.

Anyways, one of the last problems in the book illustrates one of the lessons learned I mentioned earlier in this blog. The lesson I'm referring to suggests paying attention to premises and conclusions and clearly distinguishing between the two because some answer choices will discuss the premises instead of the conclusion. The idea is that the test taker will see a topic discussed in the stimulus and select that answer choice. The question I am referring to is #121 in OG11 page 503:

aim-wsc · Posted: Fri Sep 14, 2007 8:38 pm Post subject:

Great thread!
:thumbsup:

'blogging' is lonely very lonely, at least at the starting phase... guess you have come out of that phase now...

You have more readers now.. Wink

mayonnai5e · Posted: Sat Sep 15, 2007 4:12 pm Post subject:

I've seen the SC problem several times, but have never been able to figure out what's wrong with one particular answer choice. Tonight, while I was doing a timed practice set from the OG SC set, I saw this problem again and finally figured out what the error is.

mayonnai5e · Posted: Mon Sep 17, 2007 5:21 pm Post subject:

Wow, it turns out that I'm terrible at DS under timed conditions. I just did questions 76-95 of the DS in OG11, which aren't even the hard problems, under timed conditions, and I did terribly! How bad? My hit rate untimed for questions 1-75 was roughly 93% and my hit rate tonight for this set was 75%.

Granted 1) I did this set at 1AM in the morning 2) got a total of 6 hours sleep last night and 3) worked 8 hours 4) studied permutation/combinations/probabilities for 2 hours and 5) these problems are noticeably more "tricky" than the previous 75, I'm still surprised by how many I got wrong. I stopped because it was too demotivating seeing so many errors. I noticed the time pressure forced me to move on without spending the extra seconds needed to ensure I covered all my bases. There were definitely things I simply overlooked and would have clearly seen had it not been for the time pressure.

I'll see how I fare on the next few sets, but this may be another weakness that I need to address (timed DS questions).

By the way, anyone have a similar experience and/or have advice on how to minimize this weakness?

Lesson of the day: don't do DS timed at 1 am in the morning off 6 hours sleep and after 8 hours of work and 2 hours of studying. =\

beatthegmat · Posted: Mon Sep 17, 2007 6:29 pm Post subject:

I ran into a similar situation as you did during my GMATPrep--I found that I could go through PS questions much faster than DS questions.

My workaround for this situation was to train myself to go through PS questions under 1 minute, and DS questions under 2 minutes. By keeping this pace, I was able to complete the overall quant section in time.

Otherwise--the key to getting faster in DS is just simple practice. Understand the concepts well and apply them over and over again, and you'll speed up your pace...

mayonnai5e · Posted: Tue Sep 18, 2007 1:23 am Post subject:

mayonnai5e · Posted: Tue Sep 18, 2007 8:02 am Post subject:

I've taken a lot of good lessons learned in the past few days and will post some soon...

mayonnai5e · Posted: Tue Sep 18, 2007 10:38 am Post subject:

Some important properties of 0:

--> 0 * 0 = 0
when? DS
context? xy = 0; xy >=0; xy <=0
why? unless stem states x, y are non-zero either or both can be 0

--> |0| = 0
when? DS
context? |x| used in anyway (e.g. |x-3| > y, |xy| = c)
why? special case that can be a trap

--> (0)^2 = 0
same as |0|...see above

--> 0 is non-negative
when? PS/DS
context? N is the set of first 15 non-negative integers, x and y are non-negative integers...
why? don't forget to include 0 in sets/ranges/values/etc

--> 0 is non-positive
same as above

--> 0/y = 0
when? DS/some PS
context? x/y >=0
why? 0 divided by anything is 0 so any division that does not exclude 0 as a possible value for the numerator can have 0 as the numerator

--> sq. root(0) = 0 since 0^2 = 0
when? DS
context? if sq root(x) = y, what is y?
why? may forget to leave out a possible value for x

There may be others that I've forgotten to include.

mayonnai5e · Posted: Tue Sep 18, 2007 10:59 am Post subject:

Dealing with divisors, factors and multiples:

Remember they are all different sides of the same coin (if a coin had 3 sides). What do I mean?

If X is a divsor of Y, then X is a factor of Y
4 is a divisor of 8, 4 is also a factor of 8

If X is a multiple of Y, then X is divisible by Y
4 is a multiple of 2, 4 is divisible by 2

If X is a factor of Y, then Y is divisible by X and Y is a multiple of X
4 is a factor of 8, 8 is divisible by 4, 8 is a multiple of 4

If X is divisible by Y, then X is a multiple of Y and Y is a factor of X
4 is divisible by 2, 4 is a multiple of 2 and 2 is a factor of 4

If X is a multiple of Y, then X is divisible by Y, Y is a divisor of X, and Y is a factor of X
4 is a multiple of 2, 4 is divisible by 2, 2 is a divisor of 4 and 2 is a factor of 4

If the above seems confusing, pick a few numbers and write out their prime factorizations in a tree format and stare at them for awhile. Verify the things I've said above and see how the tree describes the relationship between the three.

Remember: Multiples are at the root (top of the tree), divisors and factors are on the bottom of the tree.

Post reply or PM if this needs further explanation.

mayonnai5e · Posted: Tue Sep 18, 2007 4:41 pm Post subject:

DS. Sucks.

I finished the rest of the DS problems in the OG book and found my hit rate plummeted with the harder questions and under timed conditions. (57.5% on the last 40 questions timed). I've made a post in the MATH DS forums for suggestions/ideas on how to specifically improve this area of Q. Please reply on that thread if you have any suggestions.

http://www.beatthegmat.com/viewtopic.php?p=20991#20991

On the bright side, I actually noticed some lessons learned while doing the test. I found faster ways of doing specific problems. Hopefully the solutions will be very good and help a lot.

People on this forum have mentioned that the OG math questions are not that difficult (600-700) range so it's kind of demoralizing to see that my hit rate so low. I guess I'll just have to offset that by getting 100% of the PS questions correct. =P.

On bright side: 57.5% means huge room for improvement.

Guest · Target GMAT Score: 701

Hang in there man! You have a great approach to your studies, I'm sure you'll be improving your DS.

mayonnai5e · Posted: Fri Sep 21, 2007 12:55 am Post subject:

mayonnai5e · Posted: Fri Sep 21, 2007 2:07 am Post subject:

I haven't done any practice problems in the past two days. I finished up the DS section on Tuesday (last 60 problems) and did poorly on them so I've shifted my focus from completing the OG to focusing on lessons learned from the DS section. To that end, I've been slowly and methodically going over every solution. My approach:

1) Before looking at the solution, go through the problem again mentally and look at my practice work to see how I did the problem
2) Note any approaches that seem overly computational or require a lot of plugging in/picking numbers
3) Read official explanation.
4) Note any shortcuts or insights provided by the explanation that I overlooked or did not see.
5) Write down lesson learned on how I can see that shortcut or insight next time I see a problem with similar characteristics.

At the rate that I've been going, I can only cover 20 problems in 2 hours, which is 6 minutes per question on average.

As mentioned in this blog before, quality over quantity. Quality is where you learn the most.

Guest · Guest Target GMAT Score: 701

mayonnai5e - the link to your blog doesn't seem to be working for me..... is it still up and running or have you taken it down? thanks