Hypothesis tests & CIs for a single mean - small samples

1. A company packs sheet metal screw in 10 pound boxes. On sampling 10 of these boxes, a quality control inspector found weights with mean of 9.8 and a standard deviation of 0.19 pounds. Is she justified in concluding that boxes are not being filled to 10 pounds on the average? Use = .05.
2. The hydrocarbon emissions of a certain type of truck engine are reported to be 29.2 parts per million (ppm). When 12 new trucks with this type of engine were tested by a state emissions control agent, the emissions had a mean of 40.6 ppm with a standard deviation of 8.1 ppm. At the = .05 significance level, can the agent conclude that truck engines have a mean emission level exceeding 29.2 ppm?
3. Give the 95% C.I. for the mean for the data of Problem 1.
4. Give the 90% C.I. for the mean for the data of Problem 2.

Please help me solve these problems. This is all the information I was given so I cannot provide any table or graph. I would appreciate step-by-step explanation. Thank you!!