A boat takes 60 % more time to cover a certain distance in upstream than downstream. If speed of current is 9 km/hr., then in how much time it will go 504 km in downstream?

10.5 hr

60% = $\frac{3}{5}$

Speed ratio :-

⇒ Downstream : Upstream = 8 : 5

⇒ Boat : Current = $\frac{8+5}{2}$ : $\frac{8-5}{2}$ = $\frac{13}{2}$ : $\frac{3}{2}$

⇒ Speed of current = $\frac{3}{2}$R = 9 km/hr (given)

1R = 6

⇒ So, Downstream speed = 8 × 6 = 48 km/hr

Time to cover 504 km downstream = $\frac{504}{48}$ = 10.5 hr.