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Q:

A group of workers was put on a job. From the second day onwards, one worker was withdrawn each day. The job was finished when the last worker was withdrawn. Had no worker been withdrawn at any stage, the group would have finished the job in 55% of the time. How many workers were there in the group?

A) 50 B) 40
C) 45 D) 10

Answer:   D) 10

Explanation:

It can be solved easily through option.

        \inline \left ( 10+9+8+....+1 \right )=10\left ( 10\times \frac{55}{100} \right )

                     55 = 55     Hence correct

 

Alternatively:

        \inline \frac{n(n+1)}{2}=n\times \frac{55n}{100}

         => n= 10

In Both cases total work is 55man-days.

Q:

A can complete a piece of work in 12 days and B is 60% more efficient than A. In how many days B will complete the same work  ?

A) 8.7 hrs B) 5.2 hrs
C) 5 hrs D) 7.5 hrs
 
Answer & Explanation Answer: D) 7.5 hrs

Explanation:

Ratio of times taken by A and B = 160 : 100
A can do the work in 12 days
Let B can do the work in "D" days
=> 160:100 = 12 : D
=> D = 12 x 100/160 = 7.5 hrs

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2 6
Q:

A can finish a work in 18 days and B can do the same work in half the time taken by A. then, working together, what part of the same work they can finish in a day ?

A) Total work B) One-fourth work
C) Half work D) Two-third work
 
Answer & Explanation Answer: C) Half work

Explanation:

A can do the work = 18 days
B can do the work = 18/2 = 9 days
(A + B)'s 1 day work = 1/18 + 1/9 = 1/6
=> In 3 days = 3x1/6 = 1/2 work is completed.

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1 1
Q:

10 boys can complete a work in 7 days and 10 girls take 14 days to complete the work. How many days will 5 boys and 10 girls take to complete the work ?

A) 13 days B) 10 days
C) 7 days D) 16 days
 
Answer & Explanation Answer: C) 7 days

Explanation:

1 boy's 1 day work = 1/70
1 girl's 1 day work = 1/140
(5 boys + 10 girls)'s 1 day work
= (5/70 + 10/140) = (1/14 + 1/14) = 1/7

5 boys and 10 girls will complete the work in 7 days.

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2 32
Q:

A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days  ?

A) 9 days B) 11 days
C) 13 days D) 15 days
 
Answer & Explanation Answer: C) 13 days

Explanation:

Ratio of times taken by A and B = 100 : 130 = 10 : 13.
Suppose B takes x days to do the work.

Then, 10 : 13 :: 23 : x     =>     x = ( 23 x 13/10 )     =>     x = 299 /10.

A's 1 day's work = 1/23 ;
B's 1 day's work = 10/299 .

(A + B)'s 1 day's work = ( 1/23 + 10/299 ) = 23/299 = 113 .

Therefore, A and B together can complete the work in 13 days. 

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1 45
Q:

A laborer is engaged for 30 days on the condition that he receives Rs.25 for each day he works and is fined Rs.7.50 for each day is absent. He gets Rs.425 in all. For how many days was he absent ?

A) 10 days B) 14 days
C) 11 days D) 9 days
 
Answer & Explanation Answer: A) 10 days

Explanation:

30 x 25 = 750
               425
           -----------
               325

25 + 7.50 = 32.5

=> 325/32.5 = 10

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