Ram travelled an equal distance with the speed of 40 km/hr, 45 km/hr and 60 km/hr. What is the average speed of Ram during the whole journey? Correct to two decimal places.

Question

Question

This question was previously asked in

SSC CHSL Exam 2024 Tier-I Official Paper (Held On: 01 Jul, 2024 Shift 2)

Answer 1

Given:

Speed of the first part = 40 km/hr.

Speed of the second part = 45 km/hr.

Speed of the third part = 60 km/hr.

Formula Used:

Average speed = Total distance travelled / Total Time

Calculation:

Let each part of the journey be of equal distance, say d kilometers.

Time taken in the first part = d / 40

Time taken in the second part = d / 45

Time taken in the third part = d / 60

Total Distance = d + d + d = 3d

Total Time = (d / 40) + (d / 45) + (d / 60)

Total Time = d(1/40 + 1/45 + 1/60)

Total Time = d(9/360 + 8/360 + 6/360)

Total Time = d(23/360)

Average Speed = (3d) / \(\frac{23d}{360}\)

Average Speed = (3d × 360) / 23d

Average Speed = 1080 / 23

Average Speed ≈ 46.96 km/hr

The average speed for the whole journey is 46.96 km/hr.