4.Major League Baseball (MLB) has recently been evaluating the timing of various events during games in a effort to improve the pace of a game. MLB wants to know how long a mound visit, defined as when a coach pauses the game to visit the pitcher on the mound, takes on average. MLB randomly selects 100 games over the course of a season, and records the length, in seconds, of every mound visit that occurs in that game. This sample of mound visits can be best described as a

(a) simple random sample

(b) systematic sample

(c) stratified sample

(d) cluster sample

(e) block sample

5.Twenty volunteers with high cholesterol were selected for a trial to determine whether a new diet reduces cholesterol. The volunteers were given a low-carb, low calorie diet. After 8 weeks of the diet, the average cholesterol of the volunteers dropped a significant amount. This study is an example of

(a) A controlled experiment

(b) An uncontrolled experiment

(c) A double blind experiment

(d) A blocked design experiment

(e) An observational study

6.The department of Natural Resources (DNR) is planning a study to determine whether breakwaters help decrease erosion at a large lake. They divide the shoreline into 100-foot plots, installing some with breakwaters and some without. However, the east and the west shorelines of this lake receive very different wave patters due to the wind. The DNR suspects this will affect the responses to the breakwaters. Because of this, the DNR plans to treat each shoreline as a different group. This study is an example of

(a) an uncontrolled experiment

(b) a blocked design experiment

(c) a matched pairs experiment

(d) a stratified random sample

(e) a randomized observational study.