Math/Algebra Problems

Waiting For Grey Day

Math and I have never been close. Now with Lsat, I often come across questions that J.Y. marks as "high-school algebra" or "mathematical question in disguise" and almost always, I get them wrong.

It seems that I have to overcome my life-long battle with math. But, I think repetitively practicing these math questions aren't going to cut it. So, I want to ask those who has struggled and defeated these type of questions, what was your approach/strategy? Also, do you know any books/outside material that could supplement and improve my lack of mathematical reasoning skills?

Any advice will be greatly appreciated! Thanks in advance

inactive

I'm not a big help here but just wanted to let you know I sympathize. Math has and always will be my worst subject.

https://zippy.gfycat.com/VelvetyJauntyIchneumonfly.gif

vanessa fisher

I've never been good at math either. I found this book (which I shared here a while back) really helpful. It's called How to Lie with Statistics. It's a classic and goes through all the common ways that people lie with numbers and stats. Super short and easy to read:
https://www.amazon.ca/How-Lie-Statistics-Darrell-Huff/dp/0393310728

It really helped me because I started to realize that the "math" questions on the LSAT aren't actually math in the way we are thinking about it. Similar to how the reading comp passages are set up, it isn't so much about understanding all the content as it is understanding the underlying reasoning structures.

It is similar with the "mathy" questions on the LSAT. Once you understand the common tricks of how stats and numbers are used to confuse you with quantities and such, you will start to see the underlying problems with the questions, even if you don't get the math in a deeper sense.

Highly recommend that book. You can read it in a day. And it's fun and full of illustrations
This is the short overview:
"Darrell Huff runs the gamut of every popularly used type of statistic, probes such things as the sample study, the tabulation method, the interview technique, or the way the results are derived from the figures, and points out the countless number of dodges which are used to fool rather than to inform."

BinghamtonDave

Excellent question. These questions can be tough on the surface, but if we scratch a little, they really only test a small set of abilities. At their core, it has been my experience that these questions test our ability to tell the difference between a portion of something and the raw number. In essence, these questions test our ability to understand the difference between percentages and numbers.

Lets take a look a particularly daunting example: PT 27 Section 4 Question 14. What I recommend bringing into this question is this basic framework:

My brother and I both go to the same gym and we pay exactly the same gym fee per month: $50. What is different is that $50 is 25% of my monthly income after taxes and 10% of my brother's monthly income after taxes. In short, that gym fee is more of my monthly income than it is of my brother's. What must be true here? The answer to that question is one of the foundations one should have in place to go up against math questions on the LSAT.
My monthly income is $200
My brother's monthly income is $500

I would recommend writing out your own example of the problem above.

The final hurdle on the above example would be how to phrase the MBT: you can say my monthly income is less than my brother's, you could say that my brother's monthly income is more than mine.

Before moving on, please now try 27-4-14, with the above example in mind.

Now lets turn to 27-4-14.
The gym fee of $50 in our above example is the approval of the same amount of books: lets say 50 books. So both the first and second workers approved 50 books. For the first worker, that 50 books constituted 50% of the total work that worker did.
for the second worker that 50 books constituted 75% of the work that worker did.

What follows from the above example? 50 books is less of a percentage for worker 1 than 50 books is for worker 2. It must be, like the above example, worker 1 is my brother and worker 2 is me.

My question for you would be what if there was a third worker, in which that 50 books approved constituted 1% of their work? What would be the MBT

My next question would be what if there was a forth worker in which 50 books approved constituted 100% of their work?

In summation, the key with the math problems on the LSAT is that there is only a few ways for them to phrase these things. With some work as well as command over our own examples, we can really begin to understand these questions.

mzoodle

Vanessa makes a good point. Although I am still in the middle of studying, it appears that understanding every single sentence is not necessary. Rather, understanding the reasoning is more important. If you understand the latter you are on the path to success. Good luck.

Alex

@"Color Me Grey" I feel you.... But I honestly think with a little practice you'll be fine. In a lot of ways logic is like math and the games especially. Honestly though, they aren't even as hard as high school algebra. Don't get caught up in getting psyched out.

I really like what @"vanessa fisher" and @BinghamtonDave said, so nothing to add on that front.

akistotle

I'm terrible at math, but I like the whole pie v. slice analogy often used by J.Y. in his explanations.

Numbers (#) v. Percentages (%)
(1) The surface area of the whole pie (#): bigger or smaller
e.g. whole population increase
(2) The angle of a slice of the pie (redrawing a slice) (%): e.g. 30% to 10% (angle)
(3) The surface area of a slice of the pie (#)
e.g. the increase in the number of people with vitamin A deficiency

It's really important to identify which one of the three the stimulus is talking about.

Alex

@akistotle said:
I'm terrible at math, but I like the whole pie v. slice analogy often used by J.Y. in his explanations.

Numbers (#) v. Percentages (%)
(1) The surface area of the whole pie (#): bigger or smaller
e.g. whole population increase
(2) The angle of a slice of the pie (redrawing a slice) (%): e.g. 30% to 10% (angle)
(3) The surface area of a slice of the pie (#)
e.g. the increase in the number of people with vitamin A deficiency

It's really important to identify which one of the three the stimulus is talking about.

I agree that this is a very useful and easy to apply heuristic. Great summarization of it as well.

Waiting For Grey Day

@"Dillon A. Wright" Its so good to know I am not alone in this. Your sympathy is an encouragement

@"vanessa fisher" Thanks for your advice and recommendation. I will definitely look into this book. Its a good idea to familiarize myself with the different statistical gambits in general. I'm sure it will be a big help in the long run (not just for Lsats)

@BinghamtonDave I actually wrote this discussion after getting robbed in PT27.4.14. Its a brilliant coincidence that you chose this question as a sample explanation But reading your comment, I tried writing out my own example and it has really helped me clarify the underlying concept behind this question. Also, the process of trying to use your own example somehow makes the question less daunting. Thank you so much for taking the time to write your elaborate response! Understanding how raw numbers and percentages work together seems to be the common theme within these "mathy" questions. I have tried memorizing situations using with Powerscore Bible's #% section but for me, it was more confusing using that method. I think its better to have a more intuitive understanding, and as you suggested, using your own example until you get the hang of what actually happening under the veneer is a great way to go about achieving that. Thanks again!