Solve the all parts of given problem:

Problem: During hand-pumped rail car races, a speed of 27.2 km/h has been achieved by teams of four people. A car that has a mass equal to 320 kg is moving at that speed toward a river when Carlos, the chief pumper, notices that the bridge ahead is out. All four people (each with a mass of 75.0 kg) simultaneously jump backward off the car with a velocity that has a horizontal component of 4.00 m/s relative to the car. The car proceeds off the bank and falls into the water a horizontal distance of 20 m from the bank,

Part A: How long is the time of fall of the rail car?

Part B: What is the horizontal component of velocity of the pumpers when they hit the ground?

I need help to find how long the time of fall of the rail car.