The ratio of the speeds of a car, a train, and a bus is 5 : 9 : 4. The average speed of the car, the bus, and the train is 72 km/hr What is the average speed of the car and the train together?
Note
Let the speeds of the car, train, and bus be 5x, 9x and 4x km/hr respectively.
Then, {(5x + 9x + 4x) ÷ 3} = 72
⇒ 6x = 72
=> x = 12.
∴ Speed of the car = 60 km/hr.
Speed of the train = 108 km/hr.
∴ The average speed of car and train = (60 + 1082)km/hr = 84 km/hr.