Answer:
In this case study we have following groups:
1. Population: It had all the cars which passed the bicyclist. Out of which 3000 cars were taken.
2. Who: Each instance of a car passing a rider, means the drivers passing by.
That is the 3000 cars which passed the researcher on his bicycle.
3. What: The distance at which cars pass the bicycle rider. The distance the drivers stayed away from his bike.
