Two, trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speeds is:
Aptitude
Problems on Trains
Difficulty: Medium
Choose an option
-
A3:2
-
B4:3
-
C5:4
-
D9:16
Answer
Correct Answer: 4:3
Explanation
Given Data
- Two trains start simultaneously from opposite stations (Howrah ↔ Patna)
- After meeting, they take 9 h and 16 h respectively to reach their destinations
- Required: ratio of their speeds
Step 1: Relation between speeds and times after meetingLet speeds be v1 and v2; let meeting time from start be t.Distances before meeting: v1t and v2t.Remaining distance for Train 1 after meeting = v2t ⇒ time after meeting t1 = (v2t)/v1 = (v2/v1)t.Similarly, t2 = (v1/v2)t.Therefore, t1/t2 = (v2/v1)^2 ⇒ v1/v2 = √(t2/t1).
Step 2: Substitute valuest1 = 9 h, t2 = 16 hv1:v2 = √(16/9) = 4:3
Checks & Common Pitfalls
- Do not take speeds inversely proportional to times directly; the square-root relation applies after meeting.
- Both trains started together, so the derivation holds.
Final AnswerThe ratio of their speeds is 4:3.