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a. ee cycles to his school at an average speed of 12 km/hr. It takes him 20 minutes to reach the school., fhe wants to reach his school in 15 minutes, what should be his average speed ?, 5. The time needed to travel from one place to another is inversely proportional to the speed. A person, , travelling 72 km/hr can go from Dehradun to Lucknow in 10 hours. How fast must the person travel to, | make the trip in 9 hours ?, , 6. 28 pumps can empty a reservoir in 18 hours. In how many hours can 42 such pumps do the same work ?, 7. A stock of foodgrains is enough for 400 persons for 9 days. How long will the same stock last for 300, persons?, 8. A contractor who had a work force of 630 persons, undertook to complete a portion of a stadium in 14, months. He was asked to complete the job in 9 months. How many extra persons had he to employ ?, 9. Working 4 hours a day, Savita can type a manuscript in 15 days. How many hours a day should she work, so as to finish the work in 10 days ?, 10. A train moving at a speed of 60 km/hr covers a certain distance in 7.5 hours. What should be the speed, of the train to cover the same distance in 6 hours ?, 11. A garrison of 800 men had provisions for 39 days. However, a reinforcement of 500 men arrived. For, how many days will the food last now ?, 12. A besieged town has provisions to last for 3 weeks. Its population is 22400. How many people must be, sent away in order that the provisions may last for 7 weeks ?, 13. A hostel had rations for 60 days for 500 students. After 12 days, 300 more students join the hostel. How, , long will the remaining rations last ?, Lo