1. We want to know how much money Houston people would like to spent on restaurants every month. So we randomly find soo volunteers to do a survey questionnaire. Identify the population. A. 500 volunteers B. Houston people4. We want to know the relationship of reading speed and age. We group our people into two groups, one group is young people and one group is senior people. We let them read the same newspaper and compare their speed. Is this an experiment or observational study? A. Experiment B. Observational Study 5. You want to know the average salary of different department in University of Houston. So you are going to take samples from professors in all department and do statistics. What type of sampling is this? A. Simple random sample. B. Stratified sampling. C. None