Student: A boat moves upstream at the rate of 1 km in 20 minutes and down stream 1 km in 12 minutes. Then the speed of the current is :\nOptions:\n(A) 1 kmph\n(B) 2 kmph\n(C) 3 kmph\n(D) 2.5 kmph\n(E) 3.5 kmph.
Another student: Let's say, hmmm...

User
Rate upstream = (1/20 *60) = 3 kmph\nRate dowm stream = 1/12 * 60 = 5 kmph\nRate of the current = ½ (5-3) = 1 kmph Final answer: (A).
Assistant