Multiple choice

For covering a distance P km, a man takes t hour. He takes 40 min less if he moves 3 km/hr. faster, But if he moves slower by 2 km/hr, he takes 40 min more. then P is equal to: P किमी. की दूरी तय करने में एक व्यक्ति को t घण्टे लगते हैं। यदि वह 3 किमी./घण्टे तेज चले तो 40 मिनट कम लगते हैं लेकिन यदि वह 2 किमी./घण्टा धीमे चले तो 40 मिनट अधिक लगते हैं तो P बराबर है-

  1. 20 km 20 किमी

  2. 30 km 30 किमी

  3. 40 km 40 किमी

  4. 45 km 45 किमी

  5. None of these तय नहीं कर सकते हैं
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C Correct answer
Explanation

Let original speed be v km/hr, then P = vt. When speed increases by 3 km/hr: P/(v+3) = t - 2/3 hours. When speed decreases by 2 km/hr: P/(v-2) = t + 2/3 hours. Substituting P = vt and solving gives v = 12 km/hr, t = 10/3 hours, so P = 40 km. The key is converting 40 minutes to 2/3 hours and setting up the inverse relationship between speed and time.

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