1. The problem statement, all variables and given/known data Consider a cryogenic chemical propulsion system with Isp (specific impulse) = 450 s Enter the required propellant fraction as a proportion with at least two decimal places. The ΔVelocity is provided. ΔV = 9.6 km/s 2. Relevant equations Rocket equation: ΔV = Vex x Ln (initial mass/final mass) 3. The attempt at a solution I'm atrocious at math, yet this question has come may way nonetheless. Do I just reverse the standard rocket equation one uses to find the Delta Velocity? Propellant/final mass = ΔV x Isp? I need smart folk.