=

= where

B ---> speed of boat in still water

R---->speed of current

( By componendo and dividendo)

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.

A) 3 km/hr | B) 4 km/hr |

C) 5 km/hr | D) 6 km/hr |

Explanation:

Let P's speed = x km/hr. Then, Q's speed = (7 - x) km/ hr.

So, 24/x + 24/(7 - x) = 14

- 98x + 168 = 0

(x - 3)(x - 4) = 0 => x = 3 or 4.

Since, P is faster than Q,

so P's speed = 4 km/hr and Q's speed = 3 km/hr.

A) 12.4 hrs | B) 11.9 hrs |

C) 10.7 hrs | D) 9.9 hrs |

Explanation:

We know that

Time = Distance/speed

Required time = (10 1/4)/2 + (10 1/4)/6

= 41/8 + 41/6

= 287/24 = 11.9 hours.