The average speed of a car, a bus and a train is 72 km per hour. If the speed of the bus is 48 km per hour, then average of the speeds of the train and the car is

Correct option is D

Given:

The average speed of a car, a bus, and a train is 72 km/h.

Speed of the bus = 48 km/h.

Find the average speed of the car and the train.

Formula Used:

Average = $$\frac{\text{Sum of quantities}}{\text{Number of quantities}}$$​​

Solution:

Average speed of 3 vehicles:

Total speed = 3 × 72 = 216  km/h

Speed of bus = 48 km/h

So,

Speed of car + speed of train = 216 - 48 = 168

Average speed of car and train:

$$\frac{168}{2}$$ = 84 km/h

Alternate Solution (Exam Trick):