Standard Deviation in a Nutshell – 170 GRE Quant

Standard Deviation simply calculates how spread out, on average, numbers are away from the mean.
Don’t worry too much about the fancy formula. The GRE virtually never tests it, in my experience. I have done one example at the end of video anyway, just in case, to show how to calculate standard deviation.

First secret: Standard Deviation has nothing to do with the median!

Next secret: The Range is only Relevant if the range is zero. Otherwise you cannot use the range to calculate the standard deviation of a set of numbers.

So how is standard deviation actually tested on the GRE then?

Here is a classic question:

Six hundred applicants for several post office jobs were rated on a scale from 1 to 50 points. The ratings had a mean of 32.5 points and a standard deviation of 7.1 points. How many standard deviations above or below the mean is a rating of 48 points?

What does ‘Within 2 standard deviations’ mean? It means within 2 standard deviations above OR below the mean. We will show this, using a bell curve.

Finally, we will calculate an actual standard deviation quantity on a small set of numbers:
4, 5, 7, 11, 13

This will not only be helpful for calculating standard deviation on the GRE, but also for gaining some statistics GRE practice. These standard deviation questions should help illustrate ways to get a GRE 170 Quant score.

[sohamchowdhury]

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[julied]

I had my GRE today and scored 168 on Quant! :D I just wanted to thank you for your content because it seriously helped me out so much!

[sammysimperman]

i realize this video is four years old, but I will be taking my GRE soon and haven't taken a math class in roughly three years. These videos are acting as a big refresher for me and are actually helping me realize I know more of these concepts than I thought!

[iAnia]

Holy crap finally I understand this concept! Thank you so much!

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[brooke_ibarra]

I was always that student who was intimidated for SD questions, this was so simple and easy to understand I'm almost embarrassed that I was intimidated of these types of questions before. Goes to show you are a great teacher, thanks again for an informative video. I'm now 20 days away from my GRE

[naomishimberg]

I took my GRE today and wanted to thank you so much for all of your help. I watched your whole channel in order to prepare! Every video contained so many fantastic tricks and bits of wisdom. One heads up: I was actually asked to calculate standard deviation on the quant section. Not sure if it was the research section or not...but could be worth noting in a future video.

[cromon]

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[aditiadurkar]

I was so confused with SD. Now it's all so clear. Thanks!

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I’ve been watching almost all your GRE related videos in preparation for my GRE test this Friday. Not only have you been helpful, you have gone above and beyond on covering the easiest to most difficult problems more so than any other resource I’ve used to study. Thank you so much. I am truly so grateful for your content.

[JuanGonzalez-gqcn]

Not me watching this 30 minutes before taking the GRE. Thanks for the help!

[unapologeticallyhuman]

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[akash-dsouza]

This is so much easier than what i expected standard deviations to be. Thanks!

[cardiyansane]

i cant believe its so simple ...this whole time I have been skipping them, thankyou thankyou!

[olivianguyen]

My GRE is in a little over a week, and I've been really worried about standard deviation. Thank you so much for the video!!!

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