Important for :

1

D

Speed of the train = 6x m/s, speed of the man = x m/slength of the train = 650m,

time taken to cross a pole = 1 minute 5 seconds = 65 seconds

S = | D |

T |

6x = | 650 |

65 |

x = | 10 | = | 5 |

6 | 3 |

Speed of the man = | 5 | m/s |

3 |

Man can cross the 240m platform in | 240 |

5/3 |

= 144 seconds = 2 minutes 24 seconds

Hence, option D is correct.

2

C

Let after x hours the second train will meet the first train.Because distance is same,

S

60 (x + 2) = 80 × x

60x + 120 = 80x

80x – 60x = 120

20x = 120

x = 6 hours

Hence, option C is correct.

3

A

Let the average speed be a km/hrTime taken by aircraft (t) = | 800 |

a |

As per the condition : |
t – | 40 | = | 800 |

60 | a + 40 |

⇒ | 800 | – | 800 | = | 2 |

a | a + 40 | 3 |

⇒ | 32000 | = | 2 |

a(a + 40) | 3 |

⇒ a( a + 40 ) = 48000

⇒ a = 200Km/hr

Hence option A is correct.

4

D

Speed of the train relative to Person= | ( | 125 | ) | m/sec = 5 m/sec |

25 |

⇒ | ( | 5 × | 18 | ) | km/hr = 18 km/hr. |

5 |

Let the speed of the train be x kmph. then, relative speed = (x – 8) kmph

So, (x – 8) = 18 ⇒ x = 26 kmph

Hence, option (D) is correct.

5

A

Relative speed = 48 + 52 = 100 m/s
Total distance covered by both the trains = 160 + 200 = 360 m

Speed = | Distance |

Time |

∴ 100 = |
360 |

Time |

Hence, option A is correct.