Question

Excluding the stoppages the speed of a bus is 54 km/h and including stoppages it is 45 km/h. For how many minutes does the bus stop per hour?

Answer 1

Hint: To solve these types of questions we have to calculate the distance first the distance is covered less due to stoppage. Consider that but travelling for just an hour and solve the question.

Complete step-by-step answer:
Given:
Speed of bus excluding stoppages =$54\text{ km/h}$
Speed of bus including stoppages = $45\text{ km/h}$
To calculate: Minutes/per hour the bus stopped = ?
Distance covered by bus without stopping =$54\text{ km/h}$
Distance covered by bus with stopping =$45\text{ km/h}$
Due to stoppages it could $9\text{ km}\left( 54-45\text{ km} \right)$ less
Time taken to cover 9 km =?
$\text{time taken = }\dfrac{\text{distance}}{\text{speed}}$
Distance = 9 km
Speed = $54\text{ km/h}$
Substituting given values in the above formula we get,
Time taken =$\dfrac{9}{54}\text{ hour = }\dfrac{1}{6}\text{ hour}$.
$\Rightarrow 10\text{ minutes}$
Hence, the correct answer is $10$ minutes .

Note: For this type of question of questions always remember the formula Distance = Time $\times $ Speed.
If we want to convert speed given in km/ hour to m/s we multiply the speed in km/hr with a factor $\dfrac{5}{18}$ to convert into m/s.