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1. P is able to do a piece of work in 15 days and Q can do the same work in 20 days. If they can work together for 4 days, what is the fraction of work left? | |

A. 7/15 | B. 11/15 |

C. 2/11 | D. 8/15 |

Discuss |

answer with explanation

Answer: Option D

Explanation:

Amount of work P can do in 1 day = 1/15

Amount of work Q can do in 1 day = 1/20

Amount of work P and Q can do in 1 day = 1/15 + 1/20 = 7/60

Amount of work P and Q can together do in 4 days = 4 × (7/60) = 7/15

Fraction of work left = 1 - 7/15= 8/15

2. P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work? | |

A. 9(1/5) days | B. 9(3/5) days |

C. 9(2/5) days | D. 10 days |

Discuss |

answer with explanation

Answer: Option B

Explanation:

Amount of work P can do in 1 day = 1/16

Amount of work Q can do in 1 day = 1/12

Amount of work P, Q and R can together do in 1 day = 1/4

Amount of work R can do in 1 day = 1/4 - (1/16 + 1/12) = 3/16 - 1/12 = 5/48

=> Hence R can do the job on 48/5 days = 9 (3/5) days

3. P, Q and R can do a work in 20, 30 and 60 days respectively. How many days does it need to complete the work if P does the work and he is assisted by Q and R on every third day? | |

A. 15 days | B. 9 days |

C. 10 days | D. 14 days |

Discuss |

answer with explanation

Answer: Option A

Explanation:

Amount of work P can do in 1 day = 1/20

Amount of work Q can do in 1 day = 1/30

Amount of work R can do in 1 day = 1/60

P is working alone and every third day Q and R is helping him

Work completed in every three days = 2 × (1/20) + (1/20 + 1/30 + 1/60) = 1/5

So work completed in 15 days = 5 × 1/5 = 1

Ie, the work will be done in 15 days

4. A is thrice as good as B in work. A is able to finish a job in 60 days less than B. They can finish the work in - days if they work together. | |

A. 22 ½ days | B. 18 days |

C. 26 days | D. 24 days |

Discuss |

answer with explanation

Answer: Option A

Explanation:

If A completes a work in 1 day, B completes the same work in 3 days

Hence, if the difference is 2 days, B can complete the work in 3 days

=> if the difference is 60 days, B can complete the work in 90 days

=> Amount of work B can do in 1 day= 1/90

Amount of work A can do in 1 day = 3 × (1/90) = 1/30

Amount of work A and B can together do in 1 day = 1/90 + 1/30 = 4/90 = 2/45

=> A and B together can do the work in 45/2 days = 22 ½ days

5. A can do a particular work in 6 days . B can do the same work in 8 days. A and B signed to do it for Rs. 3200. They completed the work in 3 days with the help of C. How much is to be paid to C? | |

A. Rs. 600 | B. Rs. 420 |

C. Rs. 400 | D. Rs. 380 |

Discuss |

answer with explanation

Answer: Option C

Explanation:

Amount of work A can do in 1 day = 1/6

Amount of work B can do in 1 day = 1/8

Amount of work A + B can do in 1 day = 1/6 + 1/8 = 7/24

Amount of work A + B + C can do = 1/3

Amount of work C can do in 1 day = 1/3 - 7/24 = 1/24

work A can do in 1 day: work B can do in 1 day: work C can do in 1 day

= 1/6 : 1/8 : 1/24 = 4 : 3 : 1

Amount to be paid to C = 3200 × (1/8) = 400

Anil Peshin

2015-06-26 14:28:14

In Question no.7, you should ask in how many HOURS will B complete the work, not in how many DAYS because the answer is in Hours (12) not in days. Please slightly modify the statement, if correct

Support Team, careerbless.com

2015-06-27 17:37:01

Thanks Mr.Anil Peshin for pointing this out. It is corrected.

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varsha sharma

2015-04-07 18:20:54

A and B can complete their work in 5 days..A use his double efficiency and B use his half efficiency and complete their work in 4 days..in how many days A alone complete the work

Dev

2015-04-08 20:55:48

Let work done by A in 1 day = a (when working in normal efficiency)

and work done by B in 1 day = b (when working in normal efficiency)

Work done by A and B in 1 day = 1/5

a + b = 1/5 ----(1)

Work done by A in 1 day (in double efficiency) = 2a

Work done by B in 1 day (in half efficiency) = b/2

Work done by A and B in 1 day (A in double efficiency and B in half efficiency) = 1/4

2a + b/2 = 1/4

8a + 2b = 1 ----(2)

Solving (1) and (2)

from (1) 2a + 2b = 2/5 ----(3)

(2)-(3) : 6a = 3/5

a = 3/30 = 1/10

Work done by A in 1 day = 1/10 (when working in normal efficiency)

A alone complete the work in 10 days when working in normal efficiency.

and work done by B in 1 day = b (when working in normal efficiency)

Work done by A and B in 1 day = 1/5

a + b = 1/5 ----(1)

Work done by A in 1 day (in double efficiency) = 2a

Work done by B in 1 day (in half efficiency) = b/2

Work done by A and B in 1 day (A in double efficiency and B in half efficiency) = 1/4

2a + b/2 = 1/4

8a + 2b = 1 ----(2)

Solving (1) and (2)

from (1) 2a + 2b = 2/5 ----(3)

(2)-(3) : 6a = 3/5

a = 3/30 = 1/10

Work done by A in 1 day = 1/10 (when working in normal efficiency)

A alone complete the work in 10 days when working in normal efficiency.

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Anup

2015-04-02 14:35:05

A can do a piece of work in 14 days which B can do in 21 days .They begin together but 3 days before COMPLETION of the work ,A leaves off.
In how many days B will complete remaining work??

Dev

2015-04-08 18:06:06

I think question is wrong. 3 days before COMPLETION of the work ,A leaves off. i.e., work will be completed in 3 days after A leaves?

Probably question is to find out the total number of days in which the work will get completed

Work done by A in 1 day = 1/14

Work done by B in 1 day = 1/21

Work done by A&B in 1 day = 1/14 + 1/21 = 5/42

B works alone in the last 3 days and completes 3*1/21 = 1/7 of the work.

Remaining work = 1 - 1/7 = 6/7

Time taken by A&B to do this 6/7 of the work = (6/7)/(5/42) = 36/5 = 7.2

Total days needed to complete the work = 7.2+3=10.2 days

Probably question is to find out the total number of days in which the work will get completed

Work done by A in 1 day = 1/14

Work done by B in 1 day = 1/21

Work done by A&B in 1 day = 1/14 + 1/21 = 5/42

B works alone in the last 3 days and completes 3*1/21 = 1/7 of the work.

Remaining work = 1 - 1/7 = 6/7

Time taken by A&B to do this 6/7 of the work = (6/7)/(5/42) = 36/5 = 7.2

Total days needed to complete the work = 7.2+3=10.2 days

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azhar

2015-11-25 06:38:45

in the above problem the question is asking about time taken by B to complete remaining work not about total time required...

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sam

2015-12-23 11:40:48

@azhar, time taken by B to complete remaining work is 3 days which is given in the question, isn't it?

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amit

2015-04-01 09:36:17

20 men can complete a task in 40 days. If after every five days two men left. In how many days the work will be completed?

Vishal Bhatnagar

2016-08-14 12:22:57

20*40 = 800

So

20*5 = 100, 18*5= 90, 16*5 = 80, 14*5 =70, 12*5 = 60, 10*5 = 50, 8*5 = 40, 6*5 = 30, 4*5 = 20, 2*5=10

Total 100+90+80+70+60+50+40+30+20+10 = 550 & still 250 work is incompleted so no worker no work.

So

20*5 = 100, 18*5= 90, 16*5 = 80, 14*5 =70, 12*5 = 60, 10*5 = 50, 8*5 = 40, 6*5 = 30, 4*5 = 20, 2*5=10

Total 100+90+80+70+60+50+40+30+20+10 = 550 & still 250 work is incompleted so no worker no work.

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