11. The ratio of the speeds of a car, a train and a bus is5:9:4. The a

1.	11. The ratio of the speeds of a car, a train and a bus is5:9:4. The average speed of the car, the bus andthe train is 72 km/hr. What is the average speed ofthe car and the train together? (Bank P.O., 2010)
Answer» Let speed of car = 5xLet speed of train = 9xLet speed of bus = 4x Average speed of car, train and bus = (5x + 9x + 4x)/3= 18x/3 = 6x Then,6x = 72x = 72/6 = 12 Hence,Speed of car = 512 = 60 km/hrSpeed of train = 912 = 108 km/hrSpeed of bus = 4*12 = 48 km/hr Therefore,Average speed of car and train= (60 + 108)/2= 168/2= 84 km/hr

11. The ratio of the speeds of a car, a train and a bus is5:9:4. The average speed of the car, the bus andthe train is 72 km/hr. What is the average speed ofthe car and the train together? (Bank P.O., 2010)

Answer»

Let speed of car = 5xLet speed of train = 9xLet speed of bus = 4x

Average speed of car, train and bus = (5x + 9x + 4x)/3= 18x/3 = 6x

Then,6x = 72x = 72/6 = 12

Hence,Speed of car = 5*12 = 60 km/hrSpeed of train = 9*12 = 108 km/hrSpeed of bus = 4*12 = 48 km/hr

Therefore,Average speed of car and train= (60 + 108)/2= 168/2= 84 km/hr