GRE quant problem walkthrough: Ratios problems solved two ways

Tyler York

In this video, Achievable GRE course author Matt Roy shares two ways to solve ratios problems on the GRE exam. First, he teaches the principled algebraic method. If that does not work for you, he also teaches a more intuitive approach.

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Full GRE quant problem walkthrough: Ratios problems solved two ways video transcript:

This next problem is a ratio problem, and I'm actually going to teach you two ways to approach it. First, we're going to start off with the algebraic way. So the question states that for every one rooster there are four hints. Okay. So that is in algebraic terms of fraction where r / H = 1 / 4. Now it also states that there are 24 more.
Hens than Roosters. So you could add another part to this equation where the fraction still has R on the top, but on the bottom. We rewrite hens as simply r + 24 because there are 24 more hens than Roosters. So now we have a single equation with one variable, and now we can just solve. In order to solve for R you just need to.
Plus multiply. So we have R + 24 on the left now and we have 4R on the right. Subtract R from both sides and you get three. R = 24, so R is 8. There must be 8 Roosters. Naturally, if there are 24 more hens than Roosters, there must be 32 hens. So if there are 32 hens.
And eight Roosters. And the question asks how many total chickens are there and you just add them together. There must be 40 chickens. Now, if you're having trouble conceptualizing an algebraic equation based on just a sentence, it may be easier to think of ratio questions as comparing equally sized parts. So for example, the ratio is 1 to 4.
If you imagine there is one cage of Roosters, a large cage of Roosters, and there are four large cages of hens and they're equally sized, meaning the number of chickens in each cage is is the same. The question states that there are 24 more hens than chicken. So in how many cages must there be 24 hens?
Three because there are three more cages. Out of those 3 cages, there must be 8 in each because 24 / 3 is 8. And there you go, each cage has eight. If each cage has eight, and we have 5 total cages because we have one for rooster and four for hens, then 8 * 5 is 40. That's 40 total chickens. So that's a second way to approach it. I would definitely suggest.
Using both strategies with with each question type you get so that you get used to using the strategy so that on test day you can implement the one that that seems most natural to you or the the strategy that the question lends itself to.
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