Description : A boat goes 3.5km upstream in 24 mins and the speed of the stream is 1.5km per hour, then the speed of the boat in still water is. A) 4.3 km/hr B) 7.4 km/hr C) 5.2km/hr D) 10.25km/hr
Last Answer : ANSWER: D Explanation: Speed of upstream = 3.5 / 24 km/min = 3.5 / 24 * 60 km/hr = 8.75 km/hr Speed of the stream = ½ (a - b)km/hr = 1.5 km/hr 1.5 = ½ ( a- 8.75)km/hr a = 11.75 km/hr ... (a + b) km/hr = ½ (11.75 + 8.75) = ½(20.5) The speed of the boat in still water = 10.25 km/hr