The speed of a boat in still water is 20 km/hr and the rate of current is 5 km/hr. The distance travelled downstream in 21 minutes is:  Answers:
A) 9.75  B) 5.75  C) 8.75  D) 6.75  E) 5.15
Explanation:   Speed downstream = (20+5)= 
<gadget id="calculator">(20+5)</gadget>
<output>25</output>
25 kmph   Distance travelled= (25*(21/60))= 
<gadget id="calculator">(25*(21/60))</gadget>
<output>35/4 = around 8.75</output>
8.75 km.   ANSWER:8.75
<result>C</result>
The speed of a boat in still water is 20 km/hr and the rate of current is 5 km/hr. The distance travelled downstream in 21 minutes is: