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- GMAT Video Course
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- General GMAT Strategies - 7 videos (all free)
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- Powers and Roots - 36 videos (some free)
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- Reading Comprehension - 10 videos (all free)
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## Comment on

Introduction to Ratios## Awesome thanks for the lesson

## Ratios are important, but I

Ratios are important, but I wouldn't say they're tested as often as the super popular concepts like percents, geometry, statistics, integer properties and overlapping sets.

## I always mix up the ratios

## This is a common error.

This is a common error.

To help avoid making this mistake, it's useful to jot down the order in which you are presenting your info. Here's what I mean.

Let's say we're told that the ratio of girls to boys is 2 to 3.

Some students will take this information and write 2 : 3 (or 2/3) on their notepad. The problem with this is that it isn't clear what the two numbers represent.

Instead, I suggest that you first write: girls/boys to help you keep track of what each number represents. Then, when you write 2/3, you will be less likely to mix up the values.

You'll see that I do this throughout the videos.

## In a certain district, the

(A) 100

(B) 300

(C) 400

(D) 1,000

(E) 2,500

. Please help can't figure out .

## There are some nice

There are some nice approaches to that question here: http://www.beatthegmat.com/ratio-shorter-method-t114168.html and here https://gmatclub.com/forum/in-a-certain-district-the-ratio-of-the-number...

Let me know if you'd like me to solve as well.

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