Question 7 (1 point) For the following distribution: Pr(X=0) = 0.20 Pr(X=10) = 0.50 Pr(X=50) = 0.30 What is the mean of the distribution? 1) 15 O2) 100 03) 10 4) 20 Question 8 (1 point) Voters are placed into subgroups based on Zip Codes. A random sample of Zip Codes is selected and a random sample is taken within each of the selected Zip Codes. What type of sampling is used? 1) Simple random sampling 2) Stratified Random Sampling 3) Cluster Sampling 4) Systematic Random Sampling Question 9 (1 point) A group of statistics students decided to conduct a survey at their university to estimate the average (mean) amount of time students spent studying per week. They sampled 100 students and found a mean of 10.0 hours per week. Assuming a population standard deviation of four hours, what is the 95% level of confidence? 1) [4.200, 15.800] O2) [9.200, 10.800) 6 3) (9.800, 10.960) 4) [0.920, .0108]