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HCF = 18
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LCM = 3780
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One number = 540
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Second number = ?
🧠 Important formula:
HCF × LCM = Product of the two numbers
So,
Second number = (HCF × LCM) ÷ First number
= (18 × 3780) ÷ 540
Let’s calculate step by step:
🔹 18 × 3780 = 68,040
🔹 68,040 ÷ 540 = 126
✅ Final Answer: The second number is 126.
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wo trains start at the same time, one from Howrah to Patna and the other from Patna to Howrah.
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After they meet, the train from Howrah reaches Patna in 9 hours.
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The train from Patna reaches Howrah in 16 hours.
Let’s find the ratio of their speeds.
Let:
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Speed of train A (Howrah to Patna) = a
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Speed of train B (Patna to Howrah) = b
🧠 Key idea:
When two trains meet, the distance each travels is proportional to its speed. So,
After meeting, train A takes 9 hours to finish the remaining distance.
After meeting, train B takes 16 hours to finish its remaining distance.
Since they started at the same time and met at the same point, the time taken after meeting is inversely proportional to their speeds:
So,
a : b = √(1/9) : √(1/16)
= 1/3 : 1/4
= 4 : 3
✅ Final Answer: The ratio of their speeds is 4 : 3.