A) 5 kmph | B) 10 kmph |

C) 15 kmph | D) 45 kmph |

Explanation:

Speed of the boat downstream =

Speed of the boat upstream

The speed of the stream = .

A) 1.8 kmph | B) 2 kmph |

C) 2.2 kmph | D) 1.5 kmph |

Explanation:

Speed of Boy is B = 4.5 kmph

Let the speed of the stream is S = x kmph

Then speed in Down Stream = 4.5 + x

speed in Up Stream = 4.5 - x

As the distance is same,

=> 4.5 + x = (4.5 - x)2

=> 4.5 + x = 9 -2x

3x = 4.5

x = 1.5 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 hrs |

C) 2.5 hrs | D) 2 hrs |

Explanation:

Speed in downstream = 96/8 = 12 kmph

Speed of current = 4 km/hr

Speed of the boatman in still water = 12 – 4 = 8 kmph

Speed in upstream = 8 – 4 = 4 kmph

Time taken to cover 8 km upstream = 8/4 = 2 hours.

A) 9 and 3 kmph | B) 6 and 7 kmph |

C) 8 and 1 kmph | D) 7 and 2 kmph |

Explanation:

Downstream speed = 72km/8hrs = 9 kmph

upstream speed = 84km/12hrs = 7 kmph

speed of boat = avg of downstream and upstream speeds

speed of boat = (9+7)/2kmph = 8 kmph.

current speed = half of the difference of downstream and upstream speeds

currend speed = (9-7)/2kmph = 1 kmph

A) 16 km | B) 18 km |

C) 21 km | D) 25 km |