A man leaves his office to attend the Teacher- Parents' meet in his son's school. The school is distance of 8 km away from his office and he travels at a constant speed. He travelled half the way with the specified speed and stopped at a stationery shop for 10 minutes. To reach the school on time, he had to increase its speed by 2 km/h for the rest of the way. Next time he stopped at stationery shop for 15 minutes. By what value must he increase his speed for the remaining half of the distance to reach the school as per the schedule? 1. 1.8 kmph 2. 9.6 kmph 3. 3.6 kmph 4. 4.8 kmph