(A) 8/7 Km/h
(B) 3/2 Km/h
(C) 9/5 Km/h
(D) 14/3 Km/h
Correct Option is: D
Distance covered in downstream = 128km
Time taken in downstream = 24 hours.
Rate of downstream = distance / time = a = 128 km /24 hours = 16/3km/hr
Distance covered in upstream = 64km
Time taken in upstream = 16 hours.
Rate of upstream = distance / time = b = 64km /16hours = 4 km/hr.
Speed in still water = (a + b) / 2 = (1/2)(16/3+4) km/hr = (1/2)(28/3)km/hr
= 14/3 km/hr