A motorboat covers a certain distance downstream in a river in 3 hours and returns upstream in 4 hours. If the speed of the river current is 3 km/h, find the speed of the motorboat in still water. MCQ with Answer and Explanation
A motorboat covers a certain distance downstream in a river in 3 hours and returns upstream in 4 hours. If the speed of the river current is 3 km/h, find the speed of the motorboat in still water.
A. 27 km/h
B. 21 km/h
C. 18 km/h
D. 24 km/h
Answer: Option B
Solution (By JKExamLibrary)
Let speed of boat in still water be v. Downstream speed = v + 3, Upstream speed = v - 3. Distance is same, so 3(v + 3) = 4(v - 3) => 3v + 9 = 4v - 12 => v = 21 km/h.
A delivery van driver walks at 5 km/h and arrives 12 minutes late at his drop station. If he tracks at 8 km/h, he reaches 3 minutes early. Find the sector distance.
Explanation:
By 5:00 AM, the thief has traveled for 1 hour and covered 45 km. Relative speed = 60 - 45 = 15 km/h. Time taken to catch = 45 / 15 = 3 hours. Capture time = 5:00 AM + 3 hours = 8:00 AM.
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