(A) 8,12
(B) 8,14
(C) 6,12
(D) 6,16
Correct Option is: A
Let rate of upstream be ‘x’km/hr and downstream be ‘y’ km/hr
Then, 12/x + 18/y = 3 –1
18/x + 12/y =13/4 –2
Adding 1 and 2 we get,
30/x + 30/y = 25/4
1/x + 1/y +=5/24 –3
Subtracting 1 and 2 we get,
1/x – 1/y = 1/24 –4
Adding 3 and 4 we get,
2/x = 6/24 ; x= 8 -5
Substitute 5 in 3 we get, y=12
Speed of upstream = 8 km/hr and downstream = 12 km/hr