Aptitude Discussion

Q. |
The speed of a motor boat itself is 20 km/h and the rate of flow of the river is 4 km/h. Moving with the stream the boat went 120 km. What distance will the boat cover during the same time going against the stream? |

✔ A. |
80 km |

✖ B. |
180 km |

✖ C. |
60 km |

✖ D. |
100 km |

**Solution:**

Option(**A**) is correct

Let the distance to be covered by the boat when it is travelling against the stream be $x$.

The boat goes down the river at a speed of $20+4=24$ km/h and up the river at a speed of $20–4=16$ km/h.

Since the time taken is same which is

\(\dfrac{120}{24}=\dfrac{x}{16}\)

Therefore, $x=80$ km