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If the speed of the boat in still water is 9 km/h and the downstream speed is 6 km/h more than the upstream speed. Then find the distance covered by boat in 5 hours 20 min. downstream.1. 56 km2. 64 km3. 48 km4. 64.5 km5. 48.7 km |
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Answer» Correct Answer - Option 2 : 64 km Given: Speed of boat in still water = 9 km/h Downstream speed = 6 km/h + Upstream speed Formula used: Distance = Speed × Time Calculation: Let the speed of the stream be x km/h. Downstream speed = (9 + x) km/h Upstream speed = (9 – x) km/h According to the question, Downstream speed = 6 km/h + Upstream speed ⇒ (9 + x) = 6 + (9 – x) ⇒ 2x = 6 ⇒ x = 3 km/h Downstream speed = (9 + x) km/h ⇒ Downstream speed = 9 + 3 ⇒ Downstream speed = 12 km/h Time = 5 hours 20 min. ⇒ Time = (5 + 1/3) hours ⇒ Time = 16/3 hours Required distance = Downstream speed × Time ⇒ Required distance = 12 × 16/3 ⇒ Required distance = 64 km ∴ The distance covered by boat in 5 hours 20 min. downstream is 64 km. |
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