Multiple choice

When the speed of a train is increased by 20%, it takes 20 minutes less to cover the same distance. What is the time taken to cover the same distance with the original speed? जब ट्रेन की चाल में 20% की वृद्धि होती है, तो उसी दूरी को तय करने में 20 मिनट कम लगते हैं। मूल चाल के साथ उसी दूरी को तय करने के लिए लिया गया समय क्या है?

  1. 2 hours 20 minutes

  2. 2 hours

  3. 1 hour 40 minutes

  4. 1 hour 20 minutes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let original speed = v, original time = t. New speed = 1.2v. Since distance is same: v×t = 1.2v×(t-20). Dividing by v: t = 1.2(t-20). t = 1.2t - 24. 0.2t = 24. t = 120 minutes = 2 hours. When speed increases by 20%, time becomes 5/6 of original, saving 1/6 of the time.

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