A train took k hours to travel from place A to B. It completed 0.8k hours of its journey at an average speed of 85.3 km/h. However, due to low fuel, it completed the rest 0.2k hours of its journey at an average speed of 57.3 km/h. What was the train’s average speed for the entire journey? Unable to understand the solution present in the answer key. Thanks!

Is the answer 79.7 Kmph?

yes.

Okay so I solved it using choosing numbers.

Assume k is 10.

So 0.8k = 8 hrs journey @ 85.3 km/h

Remaining 0.2k = 2 hrs journey @ 57.3 km/h

distance = speed x time

d1 = 85.3 * 8 = 682.4 km

d2 = 57.3 * 2 = 114.6 km

average speed = (total distance)/(total time) = (682.4 + 114.6)/10 = 79.7 km/h