A runs twice as fast as B and gives B a start of 50m.How long should the racecourse be so that A and B might reach in the same time?  Choose the most appropriate option:
A) 75 m.
B) 80 m.
C) 150 m.
D) 100 m.
E) None of the above
ratio of speeds of a and b is 2:1   b is 50m away from a but we know that a covers 1 meter(2-1) more in every second than b   the time taken for a to cover 50m is   50/1= 
<gadget id="calculator">  50/1</gadget>
<output>50</output>
50m   so the total time taken by a and b to reach=2*50= 
<gadget id="calculator">2*50</gadget>
<output>100</output>
100m   ANSWER:100 m.
<result>D</result>
A runs twice as fast as B and gives B a start of 50m.How long should the racecourse be so that A and B might reach in the same time?