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Q:

A, B and C can do a piece of work in 24 days, 30 days and 40 days respectively. They began the work together but C left 4 days before the completion of the work. In how many days was the work completed?

A) 11 days B) 12 days
C) 13 days D) 14 days

Answer:   A) 11 days



Explanation:

One day's work of A, B and C = (1/24 + 1/30 + 1/40) = 1/10

C leaves 4 days before completion of the work, which means only A and B work during the last 4 days.

Work done by A and B together in the last 4 days = 4 (1/24 + 1/30) = 3/10

Remaining Work = 7/10, which was done by A,B and C in the initial number of days. 

Number of days required for this initial work = 7 days.

Thus, the total numbers of days required = 4 + 7 = 11 days.

Q:

A contractor undertake to finish a certain work in 124 days and employed 120 men. After 64 days, he found that he had already done 2/3 of the work. How many men can be discharged so that the work may finish in time ? 

A) 64 B) 62
C) 58 D) 56
 
Answer & Explanation Answer: D) 56

Explanation:

Days remaining 124 – 64 = 60 days

Remaining work = 1 - 2/3 = 1/3

Let men required men for working remaining days be 'm'

So men required = (120 x 64)/2 = (m x 60)/1 => m = 64

Men discharge = 120 – 64 = 56 men.

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4 87
Q:

A can build a wall in 16 days while B can destroy it in 8 days. A worked for 5 days. Then B joined with A for the next 2 days. Find in how many days could A build the remaining wall ?

A) 12 days B) 14 days
C) 13 days D) 16 days
 
Answer & Explanation Answer: C) 13 days

Explanation:

Now, Total work = LCM(16, 8) = 48

A's one day work = + 48/16 = + 3

B's one day work = - 48/8 = -6

Given A worked for 5 days to build the wall => 5 days work = 5 x 3 = + 15

2days B joined with A in working = 2(3 - 6) = - 6

Remaining Work of building wall = 48 - (15 - 6) = 39

Now this remaining work will be done by A in = 39/3 = 13 days.

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7 130
Q:

A mother can do a certain job in x hours. Her daughter takes twice as long to do the job. Working together, they can do the job in 6 hours. How many hours does the mother take to do the job ?

A) 3 B) 6
C) 9 D) 12
 
Answer & Explanation Answer: C) 9

Explanation:

The mother completes the job in x hours.
So, the daughter will take 2x hours to complete the same job.

 

In an hour, the mother will complete 1/x of the total job.
In an hour, the daughter will complete 1/2x of the total job.

 

So, if the mother and daughter work together, in an hour they will complete 1/x + 1/2x of the job.
i.e., in an hour they will complete 3/2x of the job.

 

The question states that they complete the entire task in 6 hours if they work together.
i.e., they complete 1/6 th of the task in an hour.

 

Equating the two information, we get 3/2x = 1/6
By solving for x, we get 2x = 18 or x = 9.

 

The mother takes 9 hours to complete the job.

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8 236
Q:

K can lay Highway road between two cities in 16 days. L can do the same job in 12 days. With the help of M, they completes the job in 4 days. How much days does it take for M alone to complete the work ?

A) 47/7 days B) 59/6 days
C) 48/5 days D) 57/5 days
 
Answer & Explanation Answer: C) 48/5 days

Explanation:

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

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

Amount of work K, L and M can together do in 1 day = 1/4

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

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

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6 169
Q:

After working for 8 days, Hari Ram finds that only 1/3 rd of the work has been done. He employs Satya who is 60% as efficient as Hari Ram. How many days more would Satya take to complete the work ?

A) 24 1/2 days B) 25 3/2 days
C) 24 2/3 days D) 26 2/3 days
 
Answer & Explanation Answer: D) 26 2/3 days

Explanation:

1/3 ---- 8

1 -------?
Hari can do total work in = 24 days

As satya is 60% efficient as Hari, then

Satya = 1/24 x 60/100 = 1/40

=> Satya can do total work in 40 days

1 ----- 40

2/3 ---- ? => 26 2/3 days.

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