GMAT Day 6 – Word Problems

Finishing the exercises of yesterday first:

This question:

Here I tried convert to normal line form and that made the exercise immensely confusing. I guess it is important in this kind of situation to make sure that I don-t transform initial equation into something else and then completelly forget about initial… the initial form might be in the already most useful one.

Check this question:

 

 

I was totally blocked after 7min… and then suddenly it dawned on me. The main biggest issues was… first of all… that I forgot one can square two sides of the equation… again this is something I don’t have as interiorized as the other rules… I remember yesterday being a bit surprised by it. Second of all… once I realized one can square both sides… then also I don’t have the relationships of (a+b)(a+b) = a^2 +2ab+ b^2 fully interiorized either… otherwise it’d have been easy to see what the solution was. On minute 7 once I realized what was going on, I did (x-y)^2 and of course one can then easily substitute and find that answer is E .

This question

I am quite happy because this was harder than the question 2 questions back, and uses not only the method I learned there but then the expansion as well. I am quite happy because I think I followed the right approach flalessly… but still it took me 2:30 min to solve. 🙁 But it’s a hard level one so I guess it makes sense?

Now check this one:

Again I solved correctly but took me 4minutes. Hmm… reason is mainly that I am not quick enough … sure these are the hardest questions but still… Also the paper and pen one uses matters… It’s important to be fully comfortable when answering the questions.

Check this question:

This one tok me 3m 15s to solve correctly. Hmm there was a quicker way :S . I could have factored things out. Taking the biggest one in each side yields a simplified 2^4 * (-1) which is very easy to solve.

Check this question:

Again I am happy I got right answer but it took me 3m 20s.

Now… I am starting to think that if I wanna get very high score… precissely what I need is to be able to answer these hardest questions in 1min 50 s. Maybe this is really what it takes to kill it… maybe the best people aren’t that much smarter… they are just able to answer these questions like me but in half the time.

Check this question:

This one totally blocked me… hmm… main problem was not realizing how to factor that quadratic polynomial. Actually I could have used the normal method I used to use  and it would have been fine. assume x^2  + mx +c = e and do the usual. When doing that then the equation is factored to (x – y)(x + 5y) = 15 . Realize that that’s the same , just written in different form.

WOA Alarm sounded… thats 1:30 hours gone just like that. Will put 1:00 more

This is my progress so far. Not bad:

So now we go to “Word Problems”.

Word problems

Ok before starting I just lost about 30 min watching some unrelated videos, not necessarily bad, but I feel I hadn’t done enough study to deserve a break XD! So anyway I just put 1 hour on the clock.

Consider this question

Now the issue is… I am getting all these questions right… but the issue is it takes me 2m 30s or so to solve (for example the one above). And the process followed on the video is pretty much what I am doing :S so basically it seems I just need to be faster overall… but if I am too fast I might make more silly mistakes. Let’s see… I hope that the more questions I do the better I’ll do.

Very careful if given a ration not to make a mistake when converting to equation.

Ok for example in this question:

Now this I solved correctly in 5 min because I did make the ratio mistake (that’s why I put the note above). But the main issue that I found is solwing me down, is that I am finding 1 variable and substituting in other equation instead of just solving the system of 2 linear equations by doing it like in the picture above. That would definitely save me time. So next time I will try that approach if it fits and see how it goes.

Ok awesome. So I did 3 more questions of the kind, in this case involving ages, and all I solved in 1m 30s approx by using the method on the picture above. It is important to have that in mind when doing the calcualtions… that one is dealing with a simple system of linear equations thats all.

Now rate questions are coming etc… time it takes if moving at x miles per minute etc. For this, having done some science helps a lot because we know of the importance of the “UNITS” and how they help to find the solutions . This is def. an advantage for someone that has done before physics or chemistry for example.

Alarm sounded 1 hour has passed

Consider this question:

Now I did the whole process correct, it’s just that I made a little mistake when solving an equation :S. Hmm… it’s a bit annoying as the conceptualization of the problem wasn’t easy and I got that right pretty quickly… just need to be careful in my calculations.

Hmm I solved another in 2m48s.

I can see that in the videos he is using a less “logical” approach, and a more “applying formulas” approach. At the end of the day it’s the same… Now, I personally prefer a logical approach not to have to memorize many things… however if I see that the time loss is really hindering me in the future, then it might make sense to try to learn the formulas and apply them more directly… but I don’t know… I hope to be able to just apply basic principles and still be able to find an answer.

Alarm sounded puntting 45m extra.

Consider this question:

Now I solved it correctly in 6m 30s which is failure totally for sure… however, important to understand what happened.

I did the process correctly but then the issue was that I got distance to be (150*7)/12. Now… the result I am looking for is that *(60/75). Now, if you calculate the distance, it is actually not an integer! So I was thinking maybe I got something wrong… The key is to realize that one does not need to calculate the distance yet… better to multiply by (60/75) because then you can factorize the 150 to take out the 75 and the calculation becomes much easier.

Distance expanding or reducing

Consider this question:

Now this took me 5 minutes that I was blocked… due to an initial stupid mistake when framing the equations. On min5  I realized and solved the problem in 1:30 after that, but it took me some time to realize that time taken by Y and time taken by B is the same! Again… sloppy although I do find the solution at the end…. Hope it won’t happen again now that I am more aware of the concept.

Besides that, I am feeling very confident I can solve these types of questions without problem, it’s just that it’s taking me a bit longer than I’d like to. I wonder if that’s what it takes to get a supe rhigh score… to not just be smart and know the fundaments… but just to know the formulas and know how to apply them quickly to get answers and move on. :S That wouldn’t be fun really.

Update: Ok now that I see the answer (which is what I got), I do see there was a smart quick way to tackle this problem even better than doing the formulas. It’s easy, just check how much the distance has reduced between the two people in 1 hour, and there u go… you just need to divide total distance by that “shrinkage rate” and that’s it. Ok, this is good to know …. in case I encounter a similar question this can definitely help.  For expanding is also easy. Find rate and apply by time.

Again check below:

Now the very sad part is that I did everything correctly but again a stupid calculation mistake I made when mentally calculating confused the heck out of me. Basically a mental calculation where 36 /3 = 13 instead of 12.

Now, I want to stop for a second (Alarm just sounded so 45 went by), and analyze what STUPID MISTAKE Is. Because whatever it is, it is comming up much more often than it should… so I might as well address it. From now on I will focus a lot to understand what each “stupid mistake” is when I make it. In this case it is clear… a faulty mental arithmetic. 36/3 should clearly be 12 not 13… Now… I can either try to avoid mental calculations for most cases for example and see if that improves my ratios… or smth like that. Let’s see, for the moment what I will do is to be VERY AWARE every time I decide to make a mental calculation, regarding the risk it entails. Let’s see if this slows me down a lot or not.

Ok, unlike the previous days, it’s now 1am so I am gonna stop here and go to sleep at 1:30 the latest. This way tomorrow I won’t have to wake up too late and I will aim to already gain some work hours in the morning, which I have not been able to do much the previoys days.

I am halfway through this section. Then I will only have 4 sections left… which are coincidentally the very toughest ones for me. Let’s see how that goes. I have not even opened the GMAT official book yet… I really wonder how will I perform with their questions. Let’s see… so far this program seems execellent from my point of view and just what I needed. After finishing the program I will then probably do a mock Quant test to see what happens.

I need probably 3 days more to finish the rest of the sections… it’ll be 7 dec by then or so? Hmm… Let’s see… maybe I can finish next sections in less if I am very diligent. Will try.

Night!