(a) draw a rough sketch of this distribution of daily expenditures

(b) if, without looking at the bill, I paid for my lunch with a 5$ bill and recieved 0.75$ in change, should I worry that i was overcharged

(c) explain logic in part (b)

This has to do with sampling distribution but I have zero idea how to go about doing this. I was also asked what a "Type II error" would be in this question, and why I might want to adopt a one-tailed test, which tail I should choose, and what would happen if I chose the wrong tail.

I know Z scores are probably used, but I can't figure out how to set this all up.