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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:

Amar can do a piece of work in 10 days. He works at it for 4 days and then Arun finishes it in 9 days. In how many days can Amar and Arun together finish the work ?

A) 4 days B) 8 days
C) 3 days D) 6 days
 
Answer & Explanation Answer: D) 6 days

Explanation:

4/10 + 9/x = 1

=> x = 15

Then both can do in

1/10 + 1/15 = 1/6

=> 6 days

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2 39
Q:

12 men complete a work in 9 days. After they have worked for 6 days, 4 more men join them. How many days will they take to complete the remaining work ?

A) 2 days B) 2.5 days
C) 2.25 days D) 3 days
 
Answer & Explanation Answer: C) 2.25 days

Explanation:

1 man's 1 day work = 1/108
12 men's 6 day's work = 1/9 x 6 = 2/3

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

16 men's 1 day work = 1/108 x 16 = 4/27
4/27 work is done by them in 1 day.

1/3 work is done by them in 27/4 x 1/3 = 9/4 days.

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Q:

P alone can complete a piece of work in 6 days. Work done by Q alone in one day is equal to one-third of the work done by P alone in one day. In how many days can the work be completed if P and Q work together  ?

A) 5 (2/3) B) 6 (3/4 )
C) 4 (1/2) D) 3
 
Answer & Explanation Answer: C) 4 (1/2)

Explanation:

Work done by P alone in one day = 1/6th of the total work done by Q alone in one day = 1/3(of that done by P in one day) = 1/3(1/6 of the total) = 1/18 of the total.

Work done by P and Q, working together in one day = 1/6 + 1/18  = 4/18 = 2/9 of the total
 
They would take 9/2 days = 4 (1/2) days to complete the work working together.
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1 39
Q:

A can do a piece of work in 30 days. He works at it for 6 days and then B finishes it in 18 days. In what time can A and B together it ?

A) 14 1/2 days B) 11 days
C) 13 1/4 days D) 12 6/7 days
 
Answer & Explanation Answer: D) 12 6/7 days

Explanation:

Let 'B' alone can do the work in 'x' days

6/30 + 18/x = 1
x = 22.5
1/30 + 1/22.5 = 7/90

=> 90/7 = 12 6/7 days

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5 139
Q:

Two persons K and L can complete a piece of work in 30 days and 45 days respectively. If they work together, what part of the work will be completed in 3 days ?

A) 1/6 B) 1/3
C) 2/3 D) 1/18
 
Answer & Explanation Answer: A) 1/6

Explanation:

K's one day's work = 1/30
L's one day's work = 1/45
(K + L)'s one day's work = 1/30 + 1/45 = 1/18

The part of the work completed in 3 days = 3 (1/18) = 1/6.

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