Question

5. A man rows a distance of 12 km in 1 hour in still water and in 80 minutes against the current.Find the time taken by him to row 45 km with the current and return to the starting point
(a) 8 hrs
(b) 15 hrs
(C) 12 hrs
(d) 16 hrs

Answer 1

Answer:

a) 8 hours

Step-by-step explanation:

speed of the boat in still water = 12 KM/hr

let speed of current be u

80 min = 4/3 hours

therefore, u= 12 -12/(4/3)= 12-9= 3 km/hr

speed of boat with the current= 12+3 = 15km/hr

speed of boat against the current= 12-3 = 9km/hr

time take to cover 45  km with the current and return to the starting point=

45/15+45/9= 3+5= 8 hours