A research wants to know if older people exercise significantly less frequently than younger people. 100 subjects are categorized into two groups: older people group vs. younger people group. The frequency of getting exercise is recorded based on the question "How many times did you exercise in the past month?"

1.What are the variable(s) in the study? (include units)

2.What is the level of measurement of the variable(s)? (Nominal, Ordinal, Continuous)

3.If there are groups are they related in any way?

4.What statistical test is most appropriate to use in analyzing the data given the information provided.