A train sets off at 9:00 am at the speed of 70 km/h. Another train starts at 9:30 am in the same direction at the rate of 84 km/h. At what time will the second train catch the first train?
Choose the correct option:
A) 11:00  B) 11:30  C) 12:00  D) 12:30  E) 1:00
In thirty minutes the first train travels 35 km.   The second train catches the first train at a rate of 84 km/h - 70 km/h = 14 km/h.   The second train will catch the first train in   35/14= 
<gadget id="calculator">  35/14</gadget>
<output>5/2 = around 2.5</output>
2.5 hours, so at 12:00 noon.   The answer is 12:00.
<result>C</result>
A train sets off at 9:00 am at the speed of 70 km/h. Another train starts at 9:30 am in the same direction at the rate of 84 km/h. At what time will the second train catch the first train?