Velocity is the rate of acceleration as measured over distance in a certain time. The time that the jump starts is denoted as 0 seconds on the graph thus the first limiting velocity that the skydiver reached was 50 m/s. That happens within 15 and 30 seconds. Thus if the velocity immediately before the parachute is opened is 50 m/s, and the velocity measured at the second limiting velocity is 10 going towards 5 m/s , then the skydiver was falling a minimum of 10 times faster.