AP Stats Test Quick Review: Random Variables

[@geenstagni1060]

I'm so surprised to see the criticisms in the comment section because I thought this video was wonderful! Thank you Michael!

[@reiweather6676]

Great video! This was an easier chapter than I thought

[@SupermodelGaming]

Great video! If only my professor knew how to fucking link the correct videos that are relevant to questions he assigns on the homework.

[@ayandas8299]

Hi Mr. Porinchak, thank you for these review videos! I had a question about transformations to the standard deviation. When do you square the b value inside the square root and when do you not square it? As I understand it, you always square the sigma value.

[@mporinchak]

If you are combining independent random variables you must always square the standard deviation (making it variance) then add together before taking the square root to go back to standard deviation. Now if you are simply converting a random variable to a new unit then you do not have to square the standard deviation.

[@ayandas8299]

@@mporinchak Thank you!!

[@makisekurisu8594]

Coronavirus: MC we don't do that here

[@richardjones6024]

This was great!

[@michaellewis7861]

I feel like often times you don’t justify something when it’s really easy to justify. With the variance being added both times, it’s obviously that it has to do with how the mean spread is effected, which it’s not whether you add or subtract it’s the same linear adjustment.

[@mporinchak]

I justify what I believe needs to be justified in a QUICK review video.

[@michaellewis7861]

Michael Porinchak oh I’m sorry. I’m just self studying all of Stats from online videos. My apologies.

[@mporinchak]

@@michaellewis7861 No worries, I am super glad you are using some of my videos to self study!!!

[@michaellewis7861]

7:00 also the data is clearly skewed left..

[@sarahbautista7893]

i think you mean skewed right. regardless, the .20 frequency for 4 tickets makes it look a bit bimodal, so no, it’s not clear.

[@michaellewis7861]

Also sorry for using your comment section as a notebook

[@michaellewis7861]

10:20 variance.

[@michaellewis7861]

For average you didn’t really explain it satisfactorily. You should’ve said that we know that people definitely buy above and below this value, and based on how far below and above, we get this number.. It is what happens when people choose discrete values indivisible by the sample size.

[@mporinchak]

These are entitled QUICK review videos not meant to justify and re-explain all of the content I have done so in class or in other videos. I do appreciate your criticism though and will worker in the future.