A bus goes to Mumbai from Delhi at the speed of 60 km/h for 60% of the journey, and covers the remaining part of its journey at the speed of 70 km/h. What is the average speed of the bus (in km/h) during the entire journey under consideration?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 64.
Speed = Distance/time
Let the distance from Delhi to Mumbai be x
Time is taken for 60% of the journey = (60/100 × x)/60
Time is taken for 60% of the journey = x/100
Time is taken for the remaining part of the journey which is 40% = (40/100 × x)/70
Time is taken for the remaining part of the journey which is 40% = x/175
⇒ Average Speed of bus for complete journey =
⇒ Average Speed of bus for complete journey =
= 17500x/275x
= 63.63 ≈ 64 64 km/h