Given a population mean of 41.8 with a standard deviation of 5.2 and a sample size of 9. What is the standard deviation of the sampling distribution of X

What does the sample size need to be if you want the standard deviation of the sampling distribution of x to be 2.6

Alocal hamburger shop sold a combined total of 601 hamburgers and cheeseburgers on friday. there were 51 more cheeseburgers sold than hamburgers. how many hamburgers were sold on friday? a local hamburger shop sold a combined total of hamburgers and cheeseburgers on friday. there were more cheeseburgers sold than hamburgers. how many hamburgers were sold on friday?

Arock was dropped from the top of a building. the function that describes the height after it was dropped is f(x)=64-16x^2. what are the zeros of the function and what do they mean?

Me because i don't understand how to do it.: )