**Sol : **(length of train+ length of bridge) = speed of train x Time

(250+150) = 20 x Speed

Speed = 400/20= 20 m/s =72 km/h

A) 1102 km | B) 1060 km |

C) 960 km | D) 1250 km |

A) 5 kmph | B) 7 kmph |

C) 3 kmph | D) 4 kmph |

Explanation:

Speed of Man = 4.5 kmph

Speed of stream = 1.5 kmph

Speed in DownStream = 6 kmph

Speed in UpStream = 3 kmph

Average Speed = (2 x 6 x 3)/9 = 4 kmph.

A) 8 kmph | B) 6 kmph |

C) 7.5 kmph | D) 5.5 kmph |

Explanation:

Speed of the stream = 1

Motor boat speed in still water be = x kmph

Down Stream = x + 1 kmph

Up Stream = x - 1 kmph

[35/(x + 1)] + [35/(x - 1)] = 12

x = 6 kmph

A) 1.5 hrs | B) 1.7 hrs |

C) 2.2 hrs | D) 3.5 hrs |

Explanation:

Let the original Speed be "s" kmph

And the usual time be "t" hrs

Given that if the bus is running at 9s/10 kmph the time is 22 hrs

=> [9s/10] x 22 = t x s

=> 99/5 = t

=> t = 19.8 hrs

Hence, if bus runs at its own speed, the time saved = 22 - 19.8 = 2.2 hrs.

A) 48 | B) 52 |

C) 38 | D) 42 |

Explanation:

Here distance d = 800 mts

speed s = 63 - 3 = 60 kmph = 60 x 5/18 m/s

time t = = 48 sec.