A boat moves upstream at the rate of 1 km in 20 minutes and down stream 1 km in 15 minutes. Then the speed of the current is : Answers.
A) 1 kmph B) 0.5 kmph C) 3 kmph D) 2.5 kmph E) 3.5 kmph
Rate upstream = (1/20 *60)= 
<gadget id="calculator">(1/20 *60)</gadget>
<output>3</output>
3 kmph   Rate down stream= 1/15 * 60= 
<gadget id="calculator">1/15 * 60</gadget>
<output>4</output>
4 kmph   Rate of the current= ½ (4-3) = 0.5 kmph   ANSWER:0.5 kmph
<result>B</result>
A boat moves upstream at the rate of 1 km in 20 minutes and down stream 1 km in 15 minutes. Then the speed of the current is :