Aresearcher wondered whether drivers treat bicycle riders differently when they wear helmets. he rigged his bicycle with an ultrasonic sensor that could measure how close each car was that passed him. he then rode on alternating days with and without a helmet. out of 4204 cars passing him, he found that when he wore his helmet, motorists passed 3 inches closer to him, on average, than when his head was bare. identify the variable ("what") recorded in this study. select all that apply. whether or not the bicycle rider is wearing a helmet the distance at which cars pass the bicycle rider the number of cars which pass the pass bicycle rider the number of days the researcher wore a helmet identify the observational units ("who") for this study. for what individual or object was each variable above recorded? the 4204 cars which passed the researcher on his bicycle the distance at which the 4204 cars passed the researcher the number of days the researcher wore a helmet the number of days the researcher rode his bicycle identify the population of interest. all cars which drive on the road all bicyclists who ride on the road with cars all cars which pass bicyclists which of these terms describes 3 inches? parameter sample statistic population