A train travels in a straight line at a constant speed of 60 km/h for a particular distance d and then travels another distance equal to 2d in the same direction at a constant speed of 80 km/h in the same direction as it was previously going.   What is the average speed of the train during the whole journey in kmph?

To find the average speed of the train during the whole journey, we need to calculate the total distance traveled and the total time taken.

Let's assume the distance traveled in the first part of the journey (at 60 km/h) is d. Therefore, the distance traveled in the second part of the journey (at 80 km/h) is 2d.

The time taken for the first part of the journey can be calculated using the formula: time = distance / speed. So, the time taken for the first part is d / 60.

Similarly, the time taken for the second part of the journey is (2d) / 80.

The total distance traveled is d + 2d = 3d.

The total time taken is (d / 60) + ((2d) / 80).

To find the average speed, we use the formula: average speed = total distance / total time.

Substituting the values, the average speed of the train during the whole journey is (3d) / ((d / 60) + ((2d) / 80)).

Simplifying the expression, we get the average speed as (3d) / ((d / 60) + (d / 40)).

Further simplifying, we can rewrite the expression as (3d) / ((2d + 3d) / 120).

Finally, simplifying the expression further, we get the average speed as (3d * 120) / (5d).

Canceling out the common factor of d, the average speed of the train during the whole journey is 360 / 5 = 72 km/h.

Therefore, the average speed of the train during the whole journey is 72 km/h.