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(d) 56.5 kgB (e) of thesec) 53.7 kg4. A train cvertakes two persons walking along a railwaytrack. The first one walks at 4.5 Km/h. The other onewalks at 5.4 Km/h. The train needs 8.4 and 8.5 secondrespectively to overtake them. What is the speed of thtrain if both the persons are walking in the samdirection as the train?(a) 66 Km/h(d) 81 Km/h(b) 72 Km/h (c) 78 Km/h(e) of these5. A 10 hectare field is reaped by 2 men, 3 womenuch time 6 men, 4hors in 10 days. If a man, a woman and a boy work |
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Answer» Let the length of the train be L km and speed be x km/hrRelative speed when the train overtakes the first person = (x-4.5)km/hr Time to overtake the first person = 8.4 sec = 8.4/3600 hour L/(x-4.5) = 8.4/36003600L = 8.4x - 37.8 ---(1)Relative speed when the train overtakes the second person = (x-5.4)km/hr Time to overtake the secomd person = 8.5 sec = 8.5/3600 hour L/(x-5.4) = 8.5/36003600L = 8.5x - 45.9 ---(2)8.4x - 37.8 = 8.5x - 45.9=> .1x = 45.9-37.8 = 8.1=> x = 81 km/hrSpeed of the train is 81 km/hr |
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