Why is 4 the smallest composite number

If benito is selecting samples of five values from the table, which row will result in the greatest mean? row 1 row 2 row 3 row 4

Icould really use some with this question.

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. what distance from city a is the point where the truck and the car will meet?