Two trains running in opposite directions cross a man standing on the platform in 32 seconds and 20 seconds respectively and they cross each other in 42 seconds. The ratio of their speed is- दो रेलगाड़ी विपरीत दिशा में चल रही है, प्लेटफार्म पर खड़े एक व्यक्ति को क्रमशः 32 सेकेण्ड और 20 में पार करती है और वे एक दूसरे को 42 सेकेण्ड में पार करती है। उनकी चालों का अनुपात है -

Let train lengths be L1 and L2, speeds be S1 and S2. A man standing still is crossed when the train passes its own length. So L1/S1 = 32 and L2/S2 = 20. Thus L1 = 32S1 and L2 = 20S2. When trains cross each other (opposite direction), relative speed is S1 + S2. Time = (L1 + L2)/(S1 + S2) = 42. Substituting: (32S1 + 20S2)/(S1 + S2) = 42. Solving: 32S1 + 20S2 = 42S1 + 42S2, giving 20S2 - 42S2 = 42S1 - 32S1, or -22S2 = 10S1, so S1/S2 = -22/10 = -11/5. Since speed is positive, S1:S2 = 11:5. The ratio is 11:5.