In a 500 m race,the ratio of the speeds of two contestants A and B is 3 : 4. A has a start of 140 m.Then,A wins by  Choose the correct choice from the following answers:
A) 60 m B) 40 m C) 20 m D) 10 m E) 50 m
Solution   To reach the winning post A will have to cover a distance of ( 500 -140)m, i.e,360m.   While A covers 3 m, B covers 4 m.   While A covers 360 m, B covers (4/3 x 360)m =480m   Thus,when A reaches the winning post, B covers 480 m and therefore remains 20 m behind.   ∴ A wins by 20 m.   Answer 20 m
<result>C</result>
In a 500 m race,the ratio of the speeds of two contestants A and B is 3 : 4. A has a start of 140 m.Then,A wins by