The speed at which a man can row a boat in still water is 21 kmph. If he rows downstream, where the speed of current is 5 kmph, what time will he take to cover 90 metres?	Choose the correct choice from the following answers
A) 23.46 B) 27.46 C) 28.46 D) 12.46 E) 25.46
Speed of the boat downstream = 21 + 5= 
<gadget id="calculator">21 + 5</gadget>
<output>26</output>
26 kmph= 26 * 5/18 = 7.22 m/s
Hence time taken to cover 90 m = 90/7.22
= 12.46 seconds.
Answer:12.46
<result>D</result>
The speed at which a man can row a boat in still water is 21 kmph. If he rows downstream, where the speed of current is 5 kmph, what time will he take to cover 90 metres?