Aptitude Discussion

Q. |
A bus without stopping travels at an average speed of 60 km/hr and with stoppages at an average speed of 40 km/hr. What is the total time taken by the bus for stoppages on a route of length 300km? |

✖ A. |
4 hr |

✖ B. |
3 hr |

✔ C. |
2.5 hr |

✖ D. |
3.5 hr |

**Solution:**

Option(**C**) is correct

Let $r$ = running time of the train

$s$= stoppage time of the train

$D$= total distance travelled by train

We have:

\(\dfrac{D}{r}=60\text{ and }\dfrac{D}{r+s}=40\)

\(\Rightarrow \dfrac{r+s}{r}=\dfrac{3}{2}\)

\(\Rightarrow \dfrac{s}{r}=\dfrac{1}{2}\)

As, $D=300$ kms

\(\dfrac{300}{r}=60\)

$⇒ r=5$ hrs and $s$ = **2.5 hr**

**Edit:** For an alternative solution, check comment by **Zoha Amjad.**

**Achin**

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**Zoha Amjad**

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Time when speed in 60 km/hr

$t= \dfrac{300}{60} = 5$ hrs

Time when speed is 40 km/hr

$t= \dfrac{300}{40} = 7.5$

Now the difference in time will be the total time taken on stoppages,

$=7.5-5 = \textbf{2.5 hrs}$

ShortCut:

Time taken by bus to go nonstop=300/60=5Hr

Time taken by bus to go with stoppages=300/40=7.5Hr

Extra time =7.5-5.0=2.5

Bus takes 2.5 hours for stoppages.