A motor boat whose speed is 18km/h in still water

Let the speed of the stream be x km/h. The speed of the boat upstream = (18 – x) km/h and The speed of the boat downstream = (18 + x) km/h. The time taken to go upstream =distance / speed = 24/18-x hours. The time taken to go downstream =distance / speed = 24/18+x hours According to the question, Since x is the speed of the stream, it cannot be negative. Therefore, x = 6 gives the speed of the stream = 6 km/h. Categories • • (31.9k) • (8.8k) • (764k) • (248k) • (10.0k) • (5.6k) • (36.4k) • (7.5k) • (10.7k) • (11.8k) • (11.2k) • (6.8k) • (4.9k) • (5.3k) • (2.8k) • (19.9k) • (959) • (2.9k) • (5.2k) • (664) • (121k) • (72.1k) • (3.8k) • (19.6k) • (1.4k) • (14.2k) • (12.5k) • (9.3k) • (7.7k) • (3.9k) • (6.7k) • (63.8k) • (26.6k) • (23.7k) • (14.6k) • (25.7k) • (530) • (84) • (766) • (49.1k) • (63.8k) • (1.8k) • (59.3k) • (24.5k)

Speed of boat = 18 km/h Let speed of the stream be =x km/h Speed of upstream = ( 18 – x ) km/hr Speed of downstream = ( 18 + x ) km/hr Distance = 24 km Time = Distance / Speed As per question, [24 / (18 – x)] – [24 / (18 + x)] = 1 24 = 1 [2x/(324 – x²)] = 1 / 24 324 – x² = 48 x² + 48x -324 = 0 [x +54] [x – 6] = 0 x = -54, x = 6 x = 6 km / hr ∴ Speed of stream =6 km / hr Related Questions • OE = 20 cm. In sector OSFT, square OEFG is inscribed. Find the area of the shaded region. • OABC is a square of side 7 cm. If OAPC is a quadrant of a circle with centre ... • A square OABC is inscribed in a quadrant OPBQ of a circle. If OA = 21 cm, find ... • OACB is a quadrant of a circle with center O and radius 3.5 cm. If OD = 2 ... • The square ABCD is divided into five equal parts, all having same area. The central part is circular ...

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Given: Speed of boat in still water = 18 km/h Distance travelled = 48 km Formula used: Time = Distance/Speed Calculation: Let the speed of the stream be ‘x’ km / h So, the speed of the boat in upstream = (18- x) km/h and the speed of the boat downstream = (18 + x) km/h The time taken to go upstream = distance/speed = 48/(18 - x) hours Similarly, the time taken to go downstream = 48/(18 + x) hours According to the question, 48/(18 - x) - 48/(18 + x) = 2 ⇒ 24 × (18 + x) - 24 × (18 - x) = (18- x) × (18 + x) ⇒ x 2 + 48x - 324 =0 ⇒ x = 6 km/h ∴ The speed of stream is 6 km/h.