Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 26)
26.
A and B can do a work in 8 days, B and C can do the same work in 12 days. A, B and C together can finish it in 6 days. A and C together will do it in :
Answer: Option
Explanation:
| (A + B + C)'s 1 day's work = | 1 | ; |
| 6 |
| (A + B)'s 1 day's work = | 1 | ; |
| 8 |
| (B + C)'s 1 day's work = | 1 | . |
| 12 |
 (A + C)'s 1 day's work |
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So, A and C together will do the work in 8 days.
Discussion:
53 comments Page 6 of 6.
Tanveer sayyed said:
3 years ago
5/24 how? anyone explain.
(1)
Pratiksha said:
2 years ago
A + B = 1/8.
B + C = 1/12.
A + B + C = 1/6.
C = A + B + C - A + B.
C = 1/6 - 1/8 = 1/24,
A = A + B + B - B + C,
A = 1/6 - 1/12 = 1/12
A + C = 1/12 + 1/24,
A + C = 1/8,
A + C = 8days.
B + C = 1/12.
A + B + C = 1/6.
C = A + B + C - A + B.
C = 1/6 - 1/8 = 1/24,
A = A + B + B - B + C,
A = 1/6 - 1/12 = 1/12
A + C = 1/12 + 1/24,
A + C = 1/8,
A + C = 8days.
(42)
Kabir NSEC said:
2 years ago
@All.
Total work: lcm of 8, 12 and 6. (For easy divisibility)= 24,
Eff = total work/days needed to do the job.
Efficiencies:
AB:24/8 = 3
BC:24/12 = 2
ABC:24/6 = 4.
Eff. of A = ABCeff - BCeff = 4-2 = 2
Eff. of C= 4-3 = 1.
So, eff of AC = 2 + 1 = 3
time to finish for AC = 24/3 = 8.
Total work: lcm of 8, 12 and 6. (For easy divisibility)= 24,
Eff = total work/days needed to do the job.
Efficiencies:
AB:24/8 = 3
BC:24/12 = 2
ABC:24/6 = 4.
Eff. of A = ABCeff - BCeff = 4-2 = 2
Eff. of C= 4-3 = 1.
So, eff of AC = 2 + 1 = 3
time to finish for AC = 24/3 = 8.
(33)
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