Error: Week 20: Estimating Var[S2]: Doubt

In the video titled " Estimating Var[S2]" of Week 20, at around 13:05 , Pratyush Sir says that when

X_i\sim N(\mu ,\sigma ^2)


\frac{\bar{X}-\mu}{\sigma}\sim N(0,1)

Here, is the corresponding screenshot:

But, I think as

\bar{X}\sim N(\mu,\frac{\sigma^2}{n})

the correct formaulation should be:

\frac{\bar{X}-\mu}{\sigma/\sqrt n}\sim N(0,1)

As a result, at around 15:04,

when Sir says that


can be seen as


it should only be


Please look into the matter once and clarify my doubt. Correct me if I am wrong !

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Hi @prassannanandjha1,
Yes you’re right, this is an error at our end.
I think it got unnoticed as this did not matter for any futher derivations.
Thanks for pointing.

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