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 : Choose the correct choice from the following:  A) 1 kmph  B) 2 kmph  C) 3 kmph  D) 2.5 kmph  E) 3.5 kmph

Rationale: rate upstream = ( 1 / 20 * 60 ) = 3 kmph rate dowm stream = 1 / 12 * 60 = 5 kmph rate of the current = ½ ( 5 - 3 ) = 1 kmph answer : a
Answer: A