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If average speed of bus for the whole journey is 25 km/hr with 28 km travelled at the speed of 22 km/hr and rest at 35 km/hr, what is the remaining distance covered at the speed of 35 km/hr?1. 160/11 km2. 230/11 km3. 13.36 km4. 140/11 km |
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Answer» Correct Answer - Option 3 : 13.36 km Given: Average speed of bus for the whole journey is 25 km/hr. 28 km are travelled at the speed of 22 km/hr and rest at 35 km/hr. Concepts used: Average speed = S1 × S2 × (d1 + d2)/(S1d2 + S2d1) Calculation: A bus covered 28 km at the speed of 22 km/hr and rest distance at the speed of 35 km/hr. Average speed = S1 × S2 × (d1 + d2)/(S1d2 + S2d1) ⇒ 25 km/hr = 22 × 35 × (28 + x)/(22 × x + 35 × 28) km/hr ⇒ 25 = 770 × (28 + x)/(22x + 980) km/hr ⇒ 25 × (22x + 980) = 770 × 28 + 770x ⇒ 25 × 22x + 25 × 980 = 21,560 + 770x ⇒ 550x + 24,500 = 21,560 + 770x ⇒ 770x - 550x = 24,500 - 21,560 ⇒ 220x = 2,940 ⇒ x = 2,940/220 km ⇒ x = 13.36 km ∴ Remaining distance travelled by bus is equal to 13.36 km. |
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