## 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?

A. 60 km/hr

B. 72 km/hr

C. 84 km/hr

D. 96 km/hr

### Answer

Correct Answer: **C. 84 km/hr **

### Solution

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 = 72 => x = 12 km/hr

Therefore, the average speed of the car and train together is = 5x+9x/2 = 7x = 7 ×12 = 84 km/hr