4161. A man travels equal distances of his journey at 40, 30 and 15 km/h. respectively. Find his average speed for whole journey?
- A. 25
- B. None of these
- C. 23
- D. 24
Check answer and explanation
Answer: 24
Explanation To find the average speed for the entire journey, let's assume the total distance traveled is 3x (since he travels equal distances at each speed). Let's denote the speeds as: S1 = 40 km/h S2 = 30 km/h S3 = 15 km/h Time taken for each segment: T1 = x / 40 T2 = x / 30 T3 = x / 15 Total time = T1 + T2 + T3 = x / 40 + x / 30 + x / 15 To find the common denominator (120): Total time = 3x / 120 + 4x / 120 + 8x / 120 = 15x / 120 Total distance = 3x Average speed = Total distance / Total time = 3x / (15x / 120) = 3 * 120 / 15 = 24