SAT Mathematics Practice Test 6

The lines shown on the graph give the positions of Paul and Mark during the race. At the start of the race, 0 seconds have elapsed, so the y-intercept of the line that represents Mark’s position during the race represents the number of yards Mark was from Paul’s position (at 0 yards) at the start of the race. Because the y-intercept of the line that represents Mark’s position is at the grid line that is halfway between 12 and 24, Mark had a head start of 18 yards.
Choices A, B, and D are incorrect. The y-intercept of the line that represents Mark’s position shows that he was 18 yards from Paul’s position at the start of the race, so he did not have a head start of 3, 12, or 24 yards.