A) 30 | B) 40 |

C) 60 | D) None of these |

Explanation:

Let t be the time after Kajol starts, when she meets Ajay, then

This should be less than 2.5 or (x+y)>120

Since y=

This (y>72) is greater than 67.5 km/h and hence Shahrukh will always overtake Ajay before he meets Kajol.

A) 1hr | B) 1 hr 20 min |

C) 1 hr 10 min | D) 50 min |

Explanation:

Let the distance and original speed be 'd' km and 'k' kmph respectively.

d/0.8k - d/k = 20/60 => 5d/4k - d/k = 1/3

=> (5d - 4d)/4k = 1/3 => d = 4/3 k

Time taken to cover the distance at original speed

= d/k = 4/3 hours = 1 hour 20 minutes.

A) 2 9/7 km | B) 3 7/5 km |

C) 1 3/4 km | D) 4 3/8 km |

Explanation:

Relative Speed = 5 ¾ - 4 ½ = 1 ¼

Time = 3 ½ h.

Distance = 5/4 x 7/2 = 35/8 = 4 3/8 km.

A) 36 kmph | B) 35 kmph |

C) 72 kmph | D) 70 kmph |

Explanation:

By car 240 km at 60 kmph

Time taken = 240/60 = 4 hr.

By train 240 km at 60 kmph

Time taken = 400/100 = 4 hr.

By bus 240 km at 60 kmph

Time taken = 200/50 = 4 hr.

So total time = 4 + 4 + 4 = 12 hr.

and total speed = 240+400+200 = 840 km

Average speed of the whole journey = 840/12 = 70 kmph.

A) 4 mile/hr | B) 6 mile/hr |

C) 2 mile/hr | D) 5 mile/hr |

Explanation:

Let the speed of river and boat be 'r' m/min and 'b' m/min.

so relative speed in upstream (b-r)m/min and in downstream (b+r)m/min.

Now in upstream distnce covered in 5 min is 5(b-r)miles

so total distnce covered => 1 + 5(b-r)miles in upstream

In downstream distance covered in 5min is 5(b+r)miles

Now 1 + 5(b-r) = 5(b+r)

1+5b-5r = 5b+5r

1 = 10r

r = 1/10 mile/min => 6 mile/hr.

A) 9 m/h | B) 3 m/h |

C) 6 m/h | D) 12 m/h |

Explanation:

let, speed of Ali=X mph and Faizer=Y mph

Now, relative speed when Ali is walking int the same direction with Faizer= (X-Y)mph

hence, according to question, 27/(X-Y)=9 ; solving X-Y=3; --- (1)

Now relative speed when walking in the opposite direction= (X+Y) mph

hence, according to question, 27/(X+y)=3; solving X+Y=9; --- (2)

solving 1 and 2 we get X=6 and Y=3, where X is the speed of Ali.