Variance and standard deviation of a discrete random variable | AP Statistics | Khan Academy

Finding the variance and standard deviation of a discrete random variable.

AP Statistics on Khan Academy: Meet one of our writers for AP¨_ Statistics, Jeff. A former high school teacher for 10 years in Kalamazoo, Michigan, Jeff taught Algebra 1, Geometry, Algebra 2, Introductory Statistics, and AP¨_ Statistics. Today he's hard at work creating new exercises and articles for AP¨_ Statistics.

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[ericmartin]

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[UnfilteredCactus]

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[BoZhaoengineering]

Statistics professor I met cannot make this clear in half semester. You did it in 6 minutes.

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[mathildahinape]

So helpful....I understand it so clearly

[elenamonat]

what formula was used for the variance?

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[zacsen]

Is it possible for the variance to be equal to 0?

[AvishkaPerera-]

Short and to the point. Thank you good sir

[TheDivoture]

Do we not minus the end result of Ex^2P(x) by the mean squared?

[Salma-kxml]

why is it - not plus in v(x), please someone answer me???

[chicken_nuggets]

I am seriously sitting here doing my finals and watching this

[채윤배-ow]

My Stat tutor can't even put right topic in the right week. So he keeps editing and it drives me crazy. Fml

[wendydugan]

mean 0.1 + 0.15 + 0, 4 + 0.25 + 0.1 = 1/ 5 = 0.20

[jaimesantos]

hey it should be 0.14 not 0.4, thus making the mean 1.58

[wendydugan]

you replace .4 to .8 in the mean calculation: all answers are off