Question
It takes 8 hours for a 600 km journey, if 120 km is done by train and the rest by car. It takes 20 minutes more if 200 km is done by train and the rest by car. The ratio of the speed of the train to that of the car is
Answer: Option B
Answer: (b)Using Rule 1,Speed of train = x kmphSpeed of car = y kmphCase I,$120/x + {600 - 120}/y$ = 8$120/x + 480/y$ = 8$15/x + 60/y$ = 1 ...(i)Case II,$200/x + 400/y$ = 8 hours 20 minutes$200/x + 400/y = 8{1}/3$ hours = $25/3$$8/x + 16/y = 1/3$$24/x + 48/y$ = 1 ...(ii)$15/x + 60/y = 24/x + 48/y$$24/x - 15/x = 60/y - 48/y$$9/x = 12/y$$x/y = 9/12 = 3/4$ = 3 : 4
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Answer: (b)Using Rule 1,Speed of train = x kmphSpeed of car = y kmphCase I,$120/x + {600 - 120}/y$ = 8$120/x + 480/y$ = 8$15/x + 60/y$ = 1 ...(i)Case II,$200/x + 400/y$ = 8 hours 20 minutes$200/x + 400/y = 8{1}/3$ hours = $25/3$$8/x + 16/y = 1/3$$24/x + 48/y$ = 1 ...(ii)$15/x + 60/y = 24/x + 48/y$$24/x - 15/x = 60/y - 48/y$$9/x = 12/y$$x/y = 9/12 = 3/4$ = 3 : 4
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