Math Test This should show a math equation: \( a^2 + b^2 = c^2 \) 🚆 Train & Platform Problem Question: A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform? 120 m 240 m 300 m None of these Solution 📘 Step-by-Step Solution: Speed of train = \[ 54 \, \text{km/hr} = 54 \times \frac{1000}{3600} = 15 \, \text{m/s} \] Time taken to pass man = 20 sec ⇒ Length of train = \[ 15 \times 20 = 300 \, \text{m} \] Time taken to pass platform = 36 sec ⇒ Total length = \[ 15 \times 36 = 540 \, \text{m} \] So, platform length = \[ 540 – 300 = \boxed{240 \, \text{m}} \] ✅ Final Answer: \(\boxed{240 \, \text{metres}}\) 🚄🚄 Two Trains Crossing Each Other Question: Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other is: 9 9.6 10 10.8 Show Solution 📘 Step-by-Step Solution: Length of first train = 140 m Length of second train = 160 m Total distance to be covered = \[ 140 + 160 = 300 \, \text{m} \] Speed of first train = \[ 60 \, \text{km/hr} = 60 \times \frac{1000}{3600} = 16.67 \, \text{m/s} \] Speed of second train = \[ 40 \, \text{km/hr} = 40 \times \frac{1000}{3600} = 11.11 \, \text{m/s} \] Relative speed (opposite direction) = \[ 16.67 + 11.11 = 27.78 \, \text{m/s} \] Time to cross each other = \[ \frac{300}{27.78} \approx \boxed{10.8 \, \text{seconds}} \] ✅ Final Answer: \(\boxed{10.8 \, \text{seconds}}\) 🚆 Train Speed Problem Question: A train running at the speed of 60 km/hr crosses a pole in 9 seconds. What is the length of the train? 120 metres 180 metres 324 metres 150 metres Show Solution 📘 Step-by-Step Solution: We use the formula: \[ \text{Distance} = \text{Speed} \times \text{Time} \] First, convert speed from km/hr to m/s: \[ 60 \, \text{km/hr} = 60 \times \frac{1000}{3600} = 16.67 \, \text{m/s} \] Now calculate distance using the time = 9 seconds: \[ \text{Distance} = 16.67 \times 9 = 150 \, \text{metres} \] ✅ Final Answer: \(\boxed{150 \, \text{metres}}\) 🚆 Train & Bridge Problem Question: The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is: 200 m 225 m 245 m 250 m Show Solution 📘 Step-by-Step Solution: Total distance covered in crossing the bridge = Length of train + Length of bridge Speed = 45 km/hr = \[ 45 \times \frac{1000}{3600} = 12.5 \, \text{m/s} \] Time = 30 seconds Total Distance = Speed × Time \[ = 12.5 \times 30 = 375 \, \text{m} \] Train length = 130 m \[ \text{Bridge length} = 375 – 130 = \boxed{245 \, \text{m}} \] ✅ Final Answer: \(\boxed{245 \, \text{metres}}\) 🚄 Two Trains from Howrah and Patna Question: 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. What is the ratio of their speeds? 2 : 3 4 : 3 6 : 7 9 : 16 Show Solution 📘 Step-by-Step Solution: Let the two trains meet at point M. 🧠 Key Concept: If two objects start at the same time and move towards each other, and after meeting, take t₁ and t₂ hours respectively to complete their journeys, then: \[ \text{Ratio of their speeds} = \sqrt{t_2} : \sqrt{t_1} \] Here, Time taken by train from Howrah after meeting = 9 hours Time taken by train from Patna after meeting = 16 hours So the ratio of speeds is: \[ \sqrt{16} : \sqrt{9} = 4 : 3 \] ✅ Final Answer: \(\boxed{4 : 3}\)