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52.
A, B and C can do a work separately in 16, 32 and 48 days respectively. They started the work together but B left off 8 days and C six days before the completion of the work. In what time is the work finished?
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10 days
-
9 days
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12 days
-
14 days
C.
12 days
Let the work is finished in x days.
Home » Aptitude » Time and Work » Question
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A and B together can do a work in 12 days. B and C together do it in 15 days. If A’s efficiency is twice that of C, then the days required for B alone to finish the work is
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- 60 days
- 30 days
- 20 days
- 15 days
(A + B)’s 1 day’s work
(B + C)’s 1 day’s work
⇒ x = 30∴ B’s 1 day’s work
= | 1 | - | 1 | [From equation (i)] |
12 | 30 |
Hence, B alone will complete the work in 20 days.
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A and B can do a piece of work in 12 days. B and C In 15 days, and C and A in 20 days. How much time will A alone take to finish the Job?
Solution
Time taken by A and B to complete a unit of work =12 days
Therefore, work done by A and B in 1 day =112 units of work
Similarly,
Work done by B and C is 1 day =115 units of work
Work done by A and C in 1 day =120 units of work
Therefore, total work done by A,B and C =12×(112+115+120)
LCM of 12,15 and 20 is 60
=12×(1×5+1×4+1×360)
=12×(1260)
=110 units of work
Therefore, work done by A alone in 1 day = Total work done − Work done by B and C
=110−115
=1×3−1×230
=130 units of work
Hence, time taken by A to complete a unit of work =30 days
Mathematics
Secondary School Mathematics VIII
Standard VIII
32