An aircraft travels 200 km up to border at 700 km/hr, then 250 km up to the target in enemy territory at 950 km/hr. After dropping the bombs, the aircraft flies at runaway speed f 1700 km/hr to the nearest border in 150 km. Then flied at 800 km/hr to the base in 300 km. Find the average speed of the sortie by using the Harmonic Mean. Also find the mission time.