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07 Jan 2020, 06:13
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
67% (02:18) correct
33%
(02:18)
wrong
based on 269
sessions
History
Date
Time
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Not Attempted Yet
A and B can complete a work working individually in 60 days and 40 days respectively. Both start working simultaneously on the work simultaneously, but B did not work on the last 4 days. Find the total number of days taken for the work to be completed.
A. 24
B. 25
C. 26.4
D. 28.2
E. 30
A. 24
B. 25
C. 26.4
D. 28.2
E. 30
08 Jan 2020, 04:16
Kudos
Bookmarks
Let’s assume the total work done to be the LCM of the times taken by A and B. The LCM of 40 and 60 is 120 units.
If A can complete 120 units in 40 days, rate of A = \(\frac{120 }{ 60}\) = 2 units per day. Similarly, rate of B = \(\frac{120 }{ 40}\) = 3 units per day.
Let the total time taken to complete the work be ‘x’ days. This means that A worked for x days and B worked for (x-4) days. Therefore,
Total work done by A = 2*x = 2x units
Total work done by B = 3*(x-4) = 3x -12 units
2x + 3x – 12 = 120, which on simplifying gives x = 132 / 5 = 26.4. The correct answer option is C.
Hope that helps!
If A can complete 120 units in 40 days, rate of A = \(\frac{120 }{ 60}\) = 2 units per day. Similarly, rate of B = \(\frac{120 }{ 40}\) = 3 units per day.
Let the total time taken to complete the work be ‘x’ days. This means that A worked for x days and B worked for (x-4) days. Therefore,
Total work done by A = 2*x = 2x units
Total work done by B = 3*(x-4) = 3x -12 units
2x + 3x – 12 = 120, which on simplifying gives x = 132 / 5 = 26.4. The correct answer option is C.
Hope that helps!
20 Feb 2020, 02:26
Kudos
Bookmarks
Bunuel
Solution:
- • Time taken by A to complete the work = \(60\) Days
• Time taken by B to come the work = \(40\) Days
- o Let the total work be \(120\) units [we should assume work as the \(LCM\) of time taken to ease calculations; \(LCM(60.40)=120\)]
o Work done by A in one day = \(\frac{120}{60}=2\) units
o Work done by B in one day = \(\frac{120}{40}=3\) units
- Work done by both of them in one day = \(2+3=5\) units
- o Work done by A in last 4 day = \(2*4 = 8\) units
• Time taken by both of them to complete the \(112\) units of work = \(\frac{112}{5 }= 22.4\) days
- o Total time taken to complete the work = \(22.4+ 4 = 26.4\) days
