[question removed by moderator]
My question is how is it that variance is unknown when they state standard deviation as 10 million?
https://www.youtube.com/watch?v=gWiftoZ2gpQ
50 min in, he gives the explanation that because it’s testing one mean and is a small sample we use the T-test. Gives no mention about standard deviation.
The standard deviation for the sample is known, but not for the population.