Boats and Streams- Aptitude Questions and Answers - in Hindi

 If a man rows at 5 km/hr in still water and 3.5 km/hr against the current,then his rate along the current is ? एक व्यक्ति शांत जल में 5 किमी / घंटा और धारा के प्रतिकूल 3.5 किमी / घंटा की चाल से तय कर सकता है। तो धारा के साथ उसकी चाल ज्ञात करें? A) 8.5 km/hr B) 6.5 km/hr C) 6 km/hr D) 4.25 km/hr Correct Answer :6.5 km/hr Explanation :If The speed of boat or boatman in calm water is u kmph and The speed of water or stream is v kmph, then:In water, the speed along with stream= (u + v) kmph Speed of current = 5 - 3.5 = 1.5 km/hr. So the speed of man along the current = 5 + 1.5 = 6.5 km/hr The speed of a boat downstream is 15 km/hr and the speed of the stream is 1.5 km/hr. The speed of the boat upstream is ? एक नाव की धारा के साथ चाल 15 किमी / घंटा है और धारा की चाल 1.5 किमी / घंटा है। तो नाव की धारा प्रतिकूल उसकी चाल क्या होगी? A) 13.5 km/hr B) 16.5 km/hr C) 12 km/hr D) 8.25 km/hr Correct Answer :12 km/hr Explanation :If The speed of boat or boatman in calm water is u kmph and The speed of water or stream is v kmph, then: Speed downstream= (u + v) kmph , In water, the speed along with stream Speed upstream = (u - v) kmph ,In water, the speed against the stream 15= u + 1.5 ⇒ u = 13.5 Speed upstream, u - v = (13.5 - 1.5) km/hr = 12 km/hr A boat goes 14 km upstream in 56 minutes. The speed of stream is 2 km/hr. The speed of boat in still water is ? एक नाव धारा के विपरीत 14 किमी 56 मिनट में तय कर सकती है। धारा की चाल 2 किमी / घंटा है। तो नाव की शांत जल में चाल क्या होगी? A) 6 km/hr B) 15 km/hr C) 14 km/hr D) 17 km/hr Correct Answer :17 km/hr Explanation :Speed upstream Speed(S) = Distance(d)/Time(t) = 14/56 km/min = 14*60/56 km/hr= 15 km/hr If The speed of boat or boatman in still water is U kmph and The speed of water or stream is V kmph, then: Speed upstream = (U - V) kmph ,In water, the speed against the stream 15 = U - 2 So speed of boat in still water , U = 17 km/hr A man can row upstream 32 km in 4 hours. If the speed of current is 2 km/hr, find how much he can go downstream in 6 hours ? एक आदमी धारा के विपरीत 4 घंटे में 32 किमी तय कर सकता है। यदि धारा की चाल 2 किमी / घंटा है, तो वह धारा के साथ वह 6 घंटे में कितनी दूरी तय कर सकता है? A) 70 km B) 72 km C) 64 km D) 81 km Correct Answer :72 km Explanation :Upstream Speed(S) = Distance(d)/Time(t) = 32/4 km/hr= 8 km/hr If The speed of boat or boatman in still water is U kmph and The speed of water or stream is V kmph, then: Speed upstream = (U - V) kmph 8 = U - 2 Speed of man in still water,U = 8 + 2 = 10 km/hr Speed of man in downstream = (U + V) kmph = (10 + 2) = 12 km/hr Now, man cover the distance in 6 hours = 12 * 6 = 72 km A man can row upstream at 15 km/h and downstream at 21 km/h. The speed of water current of the river is ? एक आदमी धारा के विपरीत 15 किमी / घंटा और धारा के साथ 21 किमी / घंटा की रफ्तार से दूरी तय कर सकता है। तो धारा की चाल क्या है? A) 8 km/h B) 6 km/h C) 3 km/h D) 5 km/h Correct Answer :3 km/h Explanation :If the speed downstream is x kmph and the speed upstream is y kmph, then: Rate of stream = 1/2 (x - y) kmph. = 1/2(21 - 15) km/h = 3 km/h A man rows downstream 60 km and upstream 36 km, taking 4 hours each time. The speed of the man is : एक आदमी 60 किमी धारा के साथ और 36 किमी धारा के विपरीत दूरी तय करता है, जिसमें हर बार उसे 4 घंटे लगते हैं। आदमी की चाल क्या है? A) 15 km/h B) 16 km/h C) 8 km/h D) 12 km/h Correct Answer :12 km/h Explanation :If the speed downstream is x kmph and the speed upstream is y kmph, then: Speed in still water = 1/2 (x + y) kmph. x = 60/4 =15 km/h y = 36/4 = 9 km/h speed of the man = (15 + 9) / 2 = 12 km/h The speed of a boat in still water is 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 12 minutes is? एक नाव की गति शांत जल में 15 किमी / घंटा है। और धारा की चाल 3 किमी / घंटा है। तो धारा के साथ 12 मिनट में वह कितनी दूरी तय करेगी? A) 1.2 km B) 1.8 km C) 2.4 km D) 3.6 km Correct Answer :3.6 km Explanation :Speed Downstream = (15 + 3) km/hr = 18 km/hr. Distance travelled =(18 * 12 / 60 )hrs = 3.6 km The speed of a boat in downstream is 12 km / h and in upstream is 8 km / h. The time taken by boat to cover 24 km in still water? प्रवाह की दिशा में किसी नौका की चाल 12 किमी/घंटा और प्रवाह के विपरीत 8 किमी/घंटा है। शांत जल में 24 किमी चलने के लिए नौका द्वारा लिया गया समय है? A) 2 hours B) 3 hours C) 2.4 hours D) 1.2 hours Correct Answer :2 hours Explanation :If The speed of boat or boatman in still water is U kmph and The speed of water or stream is V kmph, then: Speed upstream = (U - V) = 8 km/hr Speed of man in downstream = (U + V) kmph = 12 km/hr After solving above equations 2*U = 20 km/hr speed of boat in still water is,U = 10 km/hr Required time = 24 / 10 = 2.4 hr