In a 600 m race, A gave B a head start of 5 seconds and still won the race by 20 seconds. If the ratio of the speed of A to the speed of B is 2 : 1, then the speed of B is:

Correct option is B

Given:

Ratio of speed of aA and B = 2:1

Head start given by A to B = 5sec

A still won by 20 seconds

Formula Used:

Time =$$\ \frac{Distance}{Speed}$$​​

Solution:

Total time by which A won = 5 + 20 = 25 sec

Let the speed of A and B be 2x and x respectively

Then time time taken by A to finish the race  = $$\frac{600}{2x}$$​​

Time time taken by B to finish the race  =$$\frac{600}{x}$$​​

Now $$\frac{600}{x} - \frac{600}{2x} = 25 sec$$​​

​$$\frac{1200 - 600}{2x} =25$$​​

​$$x= \frac{600}{50} = 12m/sec$$​​

Speed of B = x =$$12m/sec$$​​