A person goes to his office at 1/3rd of the speed at which he returns from his office. If the avg speed during the whole trip is 18m/h. what is the speedof the person while he was going to his office?
Pick one: A) 8km/h B) 10km/h C) 12km/h D) 13km/h E) 14km/h
u = k , v= 3k   \inline \therefore \frac{2uv}{u+v}\: \: \Rightarrow \frac{2\times k\times 3k}{(k+3k)}=18   \inline \Rightarrow 1.5k = 18   \inline \Rightarrow k=12km/h   12km/h
<result>C</result>
A person goes to his office at 1/3rd of the speed at which he returns from his office. If the avg speed during the whole trip is 18m/h. what is the speedof the person while he was going to his office?