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UPSC Prelims

Mathematics

Theme:

Speed, Time and Distance / गति, समय और दूरी

Q29 2021, Speed, Time and Distance

A person X from a place A and another person Y from a place B set out at the same time to walk towards each other. The places are separated by a distance of 15 km. X walks with a uniform speed of 1.5 km/hr and Y walks with a uniform speed of 1 km/hr in the first hour, with a uniform speed of 1-25 km/hr in the second hour and with a uniform speed of 1-5 km/hr in the third hour and so on. Which of the following is/are correct?
1. They take 5 hours to meet.
2. They meet midway between A and B.
Select the correct answer using the code given below:

एक व्यक्ति X, स्थान A से तथा एक अन्य व्यक्ति Y, स्थान B से एक ही समय पर एक-दूसरे की ओर चलना आरंभ करते हैं। दोनों स्थानों के बीच की दूरी 15 km है। X, 1-5 km/hr की एकसमान चाल से चलता है और Y पहले घंटे में 1 km/hr की एकसमान चाल से, दूसरे घंटे में 1-25 km/hr की एकसमान चाल से तथा तीसरे घंटे में 1-5 km/hr की एकसमान चाल से चलता है और इसी प्रकार आगे भी चलना जारी रखता है। निम्नलिखित में से कौन-सा/कौन-से सही है/हैं?
1. उन दोनों को मिलने में 5 घंटे का समय लगेगा।
2. वे दोनों A तथा B स्थानों के बीचों-बीच मिलेंगे।
नीचे दिए गए कूट का प्रयोग कर सही उत्तर चुनिए:

Explanation Please wait..

Distance between places A and B = 15 km

Speed of X = 1.5 km/hr. So, Distance covered by X in 5 hours = 7.5 km

Speed of Y in 1st hour = 1 km/hr. So, Distance covered by Y in 1st hour = 1 km.

Similarly, Distance covered by Y in 2nd hour = 1.25 km

Distance covered by Y in 3rd hour = 1.5 km

Distance covered by Y in 4th hour = 1.75 km

Distance covered by Y in 5th hour = 2 km

So, the total distance covered by Y in 5 hours = 1 + 1.25 + 1.5 + 1.75 + 2 = 7.5 km. Hence, both the given statements are true.

व्याख्या Please wait..

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