# A and B run a 1 km race. A gives B a start of 50 m and still beats him by 15 seconds. If A runs at 8 km/h, what is the speed of B ?

(a) 4.4 km/h

(b) 5.4 km/h

(c) 6.4 km/h

(d) 7.4 km/h

**Answer: (4) 7.4 km/h**

**Explanation:-
**Speed of A = 8 km/hr

Then, speed of A = 8 x 5/18

= 20/9 m/sec

Time taken by A to cover 1 km = 1000 x 9/20

= 50 x 9

= 450 sec

Therefore, time taken by B to cover (1000 – 50) m = (450 + 15) = 465 sec

So, speed of B = 950 x 18/465 x 5

= 190 x 18/465

= 7.35

= 7.4 km/hr

Then, the speed of B is 7.4 km/hr.

Hence, the correct answer is option (d) 7.4 km/h.