The ratio of 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 together. What is the average speed of the car and the train together ?	Choices.
A) 84 km/hr  B) 74 km/hr  C) 34 km/hr  D) 64 km/hr  E) 14 km/hr
Let the speeds of the car, train and bus be 5x, 9x and 4x km/hr respectively.   Average speed = 5x + 9x + 4x/3 = 18x /3 = 6x km/hr.   Also, 6x 18  /3= 
<gadget id="calculator">18  /3</gadget>
<output>6</output>
6x km/hr.   Also, 6x= 72 =&gt; x = 12 km/hr   Therefore, the average speed of the car and train together is = = 7x = 7 x 12 = 84 km/hr.   84 km/hrnswer: 84 km/hr
<result>A</result>
The ratio of 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 together. What is the average speed of the car and the train together ?