Pls me! this is slope and i still dont get it

The contents of 3838 cans of coke have a mean of x¯¯¯=12.15x¯=12.15. assume the contents of cans of coke have a normal distribution with standard deviation of σ=0.12.σ=0.12. find the value of the test statistic zz for the claim that the population mean is μ=12.μ=12.

Ined this is due tomorrow and i dont know the answer can you find all the exponents

How can (square root of 25) ^2 be rewritten?