Answer:
Option D
Explanation:
Let rate upstream =x km/hr and rate downstream =y km/hr.
Then, 40x +55y =13 ...(i)
and 30x +44y =10 ...(ii)
Multiplying (ii) by 4 and (i) by 3 and subtracting, we get : 11y =1 or y =11.
Substituting y=11 in (i), we get : x=5.
∴ Rate in still water =12(11+5) kmph = 8 kmph.
Rate of current =12(11−5) kmph = 3 kmph.