Use Mann-Whitney U test on this problem and explain each step-by-step procedure on how to answer it manually (not using spss or r software).

Manufacturers of chips use independent sample t-test for quality assurance of their products. They use it to determine whether the weight of the chips reflects what is indicated in a bag. For this example, say manufacturers of Lay's chip randomly pulls a sample of 20 bags of chips from their latest production. After weighing all bags, the average weight of the sample is 40g with a standard deviation of 3.5g. On its label, a bag of Lay's chip weighs 42.5g. The quality assurance team wants to determine whether there the weight of the latest production (sample) and the weight indicated on the chip's label (population) is just statistically the same. For this test, the hypothesis is being tested at 95% confidence.