The speed at which a boy can row a boat in still water is 36 kmph. If he rows downstream, where the speed of current is 54 kmph, what time will he take to cover 750 metres?  Choose the correct option.
A) 29
B) 30
C) 32
D) 34
E) 36
Speed of the boat downstream = 36 + 54= 
<gadget id="calculator">36 + 54</gadget>
<output>90</output>
90 kmph= 90 * 5/18= 
<gadget id="calculator">90 * 5/18</gadget>
<output>25</output>
25 m/s   Hence time taken to cover 750 m= 750/25= 
<gadget id="calculator">750/25</gadget>
<output>30</output>
30 seconds.   Answer: 30
<result>B</result>
The speed at which a boy can row a boat in still water is 36 kmph. If he rows downstream, where the speed of current is 54 kmph, what time will he take to cover 750 metres?