Numerical Methods: Euler to Runge–Kutta · Medium problem

A skydiver's downward velocity before the parachute opens is modeled by $v' = 9.8 - kv$ (v in m/s, t in seconds), $v(0) = 0$, where $k > 0$ is an unknown drag coefficient. Euler's method with $h = 1$ s simulates the first two seconds. A radar reading shows the model's estimate of $v(2)$ is $14.7$ m/s. What value of $k$ was used? Express your answer as a common fraction.