Aptitude Discussion

Q. |
A ball is thrown twice from a place with the gap of 34 minutes between the two shots. A person approaching this point in a bus heard the second shot 33 minutes after he heard the first shot. What is the speed of bus (in kmph) if sound travels at 330 m/s? |

✖ A. |
30 |

✖ B. |
33 |

✔ C. |
36 |

✖ D. |
42 |

**Solution:**

Option(**C**) is correct

Actual time between the two shots being fired = 34 minutes.

If the man was stationary he would have heard the shots after 34 minutes. But since the car was moving towards the source, he heard the second shot after only 33 minutes = Distance travelled by the sound in 1 min.

The Bus's speed

\(=\dfrac{1}{33}\times (\text{Speed of sound}) =\dfrac{330}{33}\)m/s

= 10 m/s

$⇒$ **36 kmph**