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A and B started travelling towards each other at the same time, from places X to Y and Y to X, respectively. After crossing each other. A and B took 2.45 hours and 4.05 hours to reach Y and X, respectively. If the speed of B was 8.4 km/h, then what was the speed (in km/h) of A? |
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Answer» 3:5 Step-by-step explanation: Let say DISTANCE between A & B is D km Speed of Train starting from A = A km/Hr Speed of Train Starting from B = B km/Hr Let say after T hr they crossed each other => AT + BT = D - eq 1 => T = D/(A+B) A ( T + 25) = D => AT + 25A = D - eq2 B ( T + 9) = D => BT + 9B = D - eq 3 Eq 2 + eq3 - eq 1 => 25A + 9B = D => 25A + 9B = AT + BT - eq 4 Eq 2 - E3 AT - BT + 25A - 9B = 0 => 25A - 9B = BT - AT - eq 5 Adding eq 4 & eq 5 50A = 2BT => 25A = BT - eq 6 Eq 4 - Eq 5 18B = 2AT => 9B = AT - eq 7 eq6/eq7 25A/9B = BT/AT => 25A/9B = B/A => 25A² = 9B² => A²/B² = 9/25 => A/B = 3/5 A: B :: 3: 5 |
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