A) 1 day | B) 2 days |

C) 5 days | D) None of these |

Explanation:

Total work = 100+50 = 150man-days

In 8 days 100 man-days work has been completed. Now on 9th and 10th day there will be 25 workers. So in 2 days they wll complete additional 50 man- days work. Thus the work requires 2 more days.

A) 1900 | B) 2100 |

C) 1700 | D) 2000 |

Explanation:

Given 2000 ---- 54

The provisions for 2000 men for 39 days can be completed by 'm' men for only 20 days.

i.e, 2000 ----- 39 days == m ---- 20 days

=> m x 20 = 2000 x 39

m = 3900

So total men for 20 days is 3900 => 2000 old and 1900 new reinforcement.

Hence, reinforcement = 1900.

A) 3 hrs | B) 6 hrs |

C) 7 hrs | D) 5 hrs |

Explanation:

Suppose A, B and C take x, x/2 and x/3 respectively to finish the work.

Then, (1/x + 2/x + 3/x) = 1/2

6/x = 1/2 => x = 12

So, B takes 6 hours to finish the work.

A) 51/24 | B) 87/5 |

C) 57/12 | D) 60/11 |

Explanation:

A can complete the work in 12 days working 8 hours a day

=> Number of hours A can complete the work = 12×8 = 96 hours

=> Work done by A in 1 hour = 1/96

B can complete the work in 8 days working 10 hours a day

=> Number of hours B can complete the work = 8×10 = 80 hours

=> Work done by B in 1 hour = 1/80

Work done by A and B in 1 hour = 1/96 + 1/80 = 11/480

=> A and B can complete the work in 480/11 hours

A and B works 8 hours a day

Hence total days to complete the work with A and B working together

= (480/11)/ (8) = 60/11 days

A) 120 days | B) 119 days |

C) 118 days | D) 117 days |

Explanation:

K's work in a day(1st day) = 1/30

L's work in a day(2nd day)= -1/60(demolishing)

hence in 2 days, combined work= 1/30 - 1/60

=1/60

since both works alternatively, K will work in odd days and L will work in even days.

1/60 unit work is done in 2 days

58/60 unit work will be done in 2 x 58 days = 116 days

Remaining work = 1-58/60

= 2/60

= 1/30

Next day, it will be K's turn and K will finish the remaining 1/30 work.

hence total days = 116 + 1 = 117.

A) 2 days | B) 3 days |

C) 4 days | D) 5 days |

Explanation:

work done=total number of person x number of days;

half of work done = 140 x 66;

For half of remaining work 25 extra men are added.

Therefore, total men for half work remaining = 140 + 25 = 165;

Let 2nd half work will be completed in K days;

140 x 66 = 165 x K

K = 122;

Hence, extra days => 122-120 = 2days.