From the question atem, we know that total time t = 3 hours.
We need to know total distance so that the average speed can be calculated. Avg Speed = Total Distance/Total time.
Statement1: In 1 hour bus has travelled 1/3 distance with 60 km per hour. It have travelled 60 km in that hour and it is 1/3 of the distance. So the total distance is 60*3 = 180 km.
Now we know total distance, avg speed = total distance/ total time => 180/3
Next step is to check if statement 2 alone is sufficient.
Statement2: This statement gave the average speed for 2nd hour and 3rd hour. But we dont know the average speed in 1st hour. If we knew first hour avg speed, then we could have concluded on the total distance travelled and then the qaverage speed.
So This is not Sufficient to answer the question.
Hope this helps.
+1Kudos, if this helps