Why is it so cold, if the planet has higher mean temperature?

Standard Deviation and intervals around the mean

https://www.google.com/search?q=standard+deviation&tbm=isch&source=univ&client=firefox-b-1&sa=X&ved=2ahUKEwjYu7Tb04bgAhVReKwKHbatAiMQiR56BAgEEBE&biw=1149&bih=602

Mean versus Median

https://math.stackexchange.com/questions/3011870/mean-vs-median-geometric-interpretation

https://math.stackexchange.com/questions/947992/where-should-i-use-median-instead-of-average

When should the null hypothesis be rejected?

How do we know when to reject the null hypothesis and claim the alternative hypothesis is true?  Here are some FAQ‘s about the rejection decision that describe some ideas about Rejection Regions and also the P-value of hypothesis test. Rejection Region and P-value

Notes on Lesson 18, Linear Regression

Here are some Notes on Lesson 18, Linear Regression.