Please help me with 2. And 3.

2. Describe the differences between the z distribution and the t distribution. When is it appropriate to use the z distribution for estimation procedures? 3. A hypothetical study concerned with estimating th187e amount of marijuana use per year among a teenage population obtained a sam- ple of 110 high-school students. With the following sample statistics, construct a 95% confidence interval around the mean number of times this sample uses marijuana in a given 6-month period: X = 4.5 times per year s= 3.2 n = 110