The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 km in 4 hours, then the speed of the first train is:  Options.
A) 87 km/hr
B) 88 km/hr
C) 87.5 km/hr
D) 67 km/hr
E) 77 km/hr
Let the speed of two trains be 7x and 8x km/hr.   Then, 8x =(400/4)= 
<gadget id="calculator">(400/4)</gadget>
<output>100</output>
100   x=100/8= 
<gadget id="calculator">100/8</gadget>
<output>25/2 = around 12.5</output>
12.5   Speed of first train= (7 x 12.5) km/hr = 87.5 km/hr.   ANSWER 87.5 km/hr
<result>C</result>
The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 km in 4 hours, then the speed of the first train is: