An athlete runs 200 metres in 16 seconds what is his speed in si unit

Hello Varsha,
18/5 is use for converting meter/seconds into kilometer/hour. Actually its come from 3600/1000.

An athlete runs 200 meters race in 24 seconds. His speed (in km/hr) is : [A]28.5 [B]30 [C]24 [D]20

30 $latex Speed = \frac{Distance }{Time}=\frac{200}{24}m/s&s=1$ $latex =>\frac{200}{24}m/s=\frac{200}{24}\times \frac{18}{5}=30 km/hr&s=1$

Hence option [B] is the right answer.