P,Q & R are on a journey by scorpio. P drives during the 1st 2 hrs at an average speed of 60 km/hr. Q drives during the next 3 hrs at an average speed of 58 km/hr R drives for the next 4 hrs at an average speed of 62 km/hr. They reached their destination after exactly 5 hrs. Their main speed is. a) 60 2/9 b) 62 2/9 c) 60 4/8 d) 62 4 /8