question_answer

A boat travels 50 km east, then 120 km North and finally it comes back to the starting point through the shortest distance. The total time of journey is 3 h. What is the average velocity, in\[km\text{ }{{h}^{-1}},\]over the entire trip?

A)  zero                     

B)         100

C)  17                         

D)         33.33

E)  86.7

Correct Answer: B

Solution :

\[Time=\frac{distance}{average\text{ }velocity}\] \[\Rightarrow \]\[Average\text{ }velocity=\frac{distance}{time}\] \[v=\frac{130+120+50}{3}=\frac{300}{3}=100\,km/h\]