A) 14.4 sec | B) 15.5 sec |

C) 18.8 sec | D) 20.2 sec |

Explanation:

Let the length of the train be L metres

Speed of first train = m/hour

Speed of secxond train = m/hour

When running in opposite directions, relative speed = 200 L + 300 L m/hour

Distance to be covered = L + L = 2L metre

Time taken = sec

=14.4 sec

A) 28 kmph | B) 24 kmph |

C) 26 kmph | D) 32 kmph |

Explanation:

Total time taken = k/40 + 2k/20 hours

= 5k/40 = k/8 hours

Average speed = 3k/(k/8) = 24 kmph.

A) 400 m | B) 300 m |

C) 500 m | D) 600 m |

Explanation:

Speed = 78 x 5/18 = 65/3 m/sec.

Time = 1 min = 60 sec.

Let the length of the train be x meters.

Then, (900 + x)/60 = 65/3

x = 400 m.

A) 68 kmph | B) 52 kmph |

C) 76 kmph | D) 50 kmph |

Explanation:

Let the speed of the faster train be 'X' kmph,

Then their relative speed= X - 48 kmph

To cross slower train by faster train,

Distance need to be cover = (400 + 600)m = 1 km. and

Time required = 180 sec = 180/3600 hr = 1/20 hr.

Time = Distance/Speed

=> 1/20 = 1/(x-48)

X = 68 kmph

A) 10 sec | B) 48 sec |

C) 36 sec | D) 56 sec |

Explanation:

Given speed of jogger = 9 kmph

Speed of train = 45 kmph

As they are in same direction,

Relative speed = 45 - 9 = 36 kmph = 36x5/18 = 10 m/s

Distance = 240 + 120 = 360 mts

Time = distance/speed = 360/10 = 36 sec.

A) 1 : 2 | B) 3 : 1 |

C) 4 : 7 | D) 3 : 2 |

Explanation:

Let the speeds of the two trains be x m/sec and y m/sec respectively.

Then, length of the first train = 27 x meters, and

length of the second train = 17 y meters.

(27 x + 17 y) / (x + y) = 23

=> 27 x + 17 y = 23 x + 23 y

=> 4 x = 6 y

=> x/y = 3/2.