1. An educational researcher explores whether there is a link between the amount of time someone spends studying and the grade they get in a particular class. 2. A human resources professional wonders if how much money a person earns can impact the extent to which an individual experiences job satisfaction. 3. A study was done to find if fuel types affect the engine's performance in a car. 4. A study was conducted to determine the effect of climbing to high altitudes on a climber's memory. 5. Students of different ages were given the same math test. Researchers looked at the number of correct answers on the test.