An engine moves at the speed of 30 kmph without any coaches attached to it.Speed of the train reduces at the rate that varies directly as the square root of the number of coaches attached.When 9 coaches are attached speed decreases to 18 kmph. What will be the speed of train when 16 coaches are attached. Choose one:
A) 14
B) 16
C) 18
D) 20
E) 22
1.   No. of coaches =9   sqr root=3   speed decreases by 12   12=k*3   k=4   No. of coaches=16   swr root=4   decrease=4*4= 
<gadget id="calculator">4*4</gadget>
<output>16</output>
16   New speed=30-16= 
<gadget id="calculator">30-16</gadget>
<output>14</output>
14   14
<result>A</result>
An engine moves at the speed of 30 kmph without any coaches attached to it.Speed of the train reduces at the rate that varies directly as the square root of the number of coaches attached.When 9 coaches are attached speed decreases to 18 kmph. What will be the speed of train when 16 coaches are attached.