Help PlSss there’s people not helping I really need to bring my grades up

Given the following sampling distribution of one mean with a sample size 49, from a normally distributed population,find the population standard deviation, o.79828588912497

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.

The figure below shows rectangle abcd and the triangle eca on a coordinate plane.which of the following expressions represents the perimeter of triangle of triangle eca in units