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Q:

Relation Between Efficiency and Time 

Additional Details

A is twice as good a workman as B and is therefore able to finish a piece of work in 30 days less than B.In how many days they can complee the whole work; working together?

 

Answer:
Q:

A take twice as much time as B or thrice as much time to finish a piece of work. Working together, they can finish the work in 2 days. B can do the work alone in  ?

A) 8 hrs B) 12 hrs
C) 6 hrs D) 4 hrs
 
Answer & Explanation Answer: C) 6 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.
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1 16
Q:

Sixty men can stitch 150 shirts in 30 days working 8 hours a day. In how many days can 35 men stitch 200 shirts working 6 hours a day ?

A) 87.5 B) 89
C) 91.5 D) 93.5
 
Answer & Explanation Answer: C) 91.5

Explanation:

We have M1 D1 H1 / W1 = M2 D2 H2 / W2 (Variation rule)
(60 x 30 x 8)/ 150 = (35 x D2 x 6) / 200
D2 = (60 x 30 x 8 x 200) / (150 x 35 x 6) => D2 = 91.42 days =~ 91.5 days.

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1 33
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 51
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 38
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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