Answer: I think Its the Height is 11.76 Meters (38.582677 Feet) between the bridge and the ground
Explanation: Supposing that where not counting air resistance in the equation, the equation 
states that 1/2 multiplied by earths gravitational acceleration multiplied by the amount of time to reach the bottom: 2.4 seconds equals 11.76 meters of height between the bridge and the ground.
Ans; see attached file for calculation and answer
Explanation:
1) 15 / 12 = 1.25 ratio
2) to increase acceleration 1.25 times (with same F, or same engine) you have to lower mass 1.25 times
3) 1515/1.25 = 1212 kg
choose A
