Duke's Brand Dog Treats claim to contain 59 treats in each of its jumbo packages of treats. The standard deviation for the number of treats in each package is 20 (you can think of this claim as representing the whole population of jumbo packages dog treats). You decide to test this because you (and your dog) think the jumbo packages of treats contain a different number of treats than the Duke brand claims. You count the number of treats in a sample of 16 jumbo packages and find that their average is 50 treats per package. Calculate a one sample z-test to test whether your sample of dog treats reflects the population (what the company claims). Put your value below and round your answer to 2 decimal places.