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 5 of 6.
Vishal sinha said:
6 years ago
It can be done in a much simpler way.
(A+B)'s 1-day work = 1/8.
(B+C)'s 1-day work = 1/12.
(A+B)+(B+C)'s 1 day work= 1/8+1/12.
B+(A+B+C)=5/24,
B=5/24-1/6,
B=1/24.
So, A+B+C=1/6,
Putting the value of B.
(A+C)'s 1 day work = 1/6 - 1/24 = 1/8.
Time taken = 8 days.
(A+B)'s 1-day work = 1/8.
(B+C)'s 1-day work = 1/12.
(A+B)+(B+C)'s 1 day work= 1/8+1/12.
B+(A+B+C)=5/24,
B=5/24-1/6,
B=1/24.
So, A+B+C=1/6,
Putting the value of B.
(A+C)'s 1 day work = 1/6 - 1/24 = 1/8.
Time taken = 8 days.
Rehan said:
6 years ago
(A+B)+(B+C)+(C+A) = 2 (A+B+C).
1/8 + 1/12+ (C+A) = 2 * 1/6.
1/8 + 1/12+ (C+A) = 2 * 1/6.
PRASHANT VERMA said:
6 years ago
1/8+1/12-1/6=1/24.
BECAUSE A+B = 8
B+C = 12
A+C = ?
A+B+C = 6.
BECAUSE A+B = 8
B+C = 12
A+C = ?
A+B+C = 6.
Kesavan said:
5 years ago
Given question,
A + B = 1/8 days.
B + C = 1/12 days.
A + B + C = 1/6 days.
We want C+A,
(A+B) + (B+C) + (A+C) =2 (A+B+C)------->1.
Now substitute all the values in Eqn( 1).
1/8 + 1/12 + (A+C) = 2 (1/6),
(A+C) = 1/3 - 1/8 - 1/12.
Now I Take lcm, (8-3-2/24).
8-5/24----->3/24.
A+C = 1/8 days.
so the answer is 8 days.
A + B = 1/8 days.
B + C = 1/12 days.
A + B + C = 1/6 days.
We want C+A,
(A+B) + (B+C) + (A+C) =2 (A+B+C)------->1.
Now substitute all the values in Eqn( 1).
1/8 + 1/12 + (A+C) = 2 (1/6),
(A+C) = 1/3 - 1/8 - 1/12.
Now I Take lcm, (8-3-2/24).
8-5/24----->3/24.
A+C = 1/8 days.
so the answer is 8 days.
(8)
Pranav Ambore said:
5 years ago
A+B+C=1/6 ---------> (1)
A+B=1/8 --------------> (2)
B+C=1/12-------------> (3)
By using(1) & (2).
1/8+c = 1/6.
c = 1/24.
By using(1) & (3).
A+1/12 = 1/6.
A = 1/12.
A + C = 1/12+ 1/24 = 1/8.
8 days.
A+B=1/8 --------------> (2)
B+C=1/12-------------> (3)
By using(1) & (2).
1/8+c = 1/6.
c = 1/24.
By using(1) & (3).
A+1/12 = 1/6.
A = 1/12.
A + C = 1/12+ 1/24 = 1/8.
8 days.
(19)
Jigme Wangchuk said:
5 years ago
Lcm of 8 and 12 =24.
A + B works 24/3 = 3 units.
B + C works 24/12 = 2 units.
A + B + C works 24/6 = 4 units.
Now, A works 4-2= 2 units.
C works 4-3= 1 units.
Total work done by A+C = 2+1= 3 units.
Therefore, 24/3= 8.
A + B works 24/3 = 3 units.
B + C works 24/12 = 2 units.
A + B + C works 24/6 = 4 units.
Now, A works 4-2= 2 units.
C works 4-3= 1 units.
Total work done by A+C = 2+1= 3 units.
Therefore, 24/3= 8.
(13)
Pandeswari Durai Pandi said:
5 years ago
@Nanthu.
Thank you for using LCM method it makes me to understand it easily.
Thank you for using LCM method it makes me to understand it easily.
SIVA said:
5 years ago
Good explanation. Thanks all.
(2)
Gaurab.bc said:
4 years ago
A+B = 8
B+C=12
A+B+C=6.
Total work LCM=24 unit work for each group to do in 1 day = 24/8=3, 24/12=2 24/6 =4 (3,2,4)
So, A alone efficiency = (A+B+C)-(B+C)=4-2 =2 so work done by in A=24/2 =12 day simiarly by B = 24/1 = 24 days.
Finally, LCM for A and B= 24 , unit work for each = 2 and 1.
So total efficency = 1+2 =3 and work done by A+B = 24/3 = 8 DAYS.
B+C=12
A+B+C=6.
Total work LCM=24 unit work for each group to do in 1 day = 24/8=3, 24/12=2 24/6 =4 (3,2,4)
So, A alone efficiency = (A+B+C)-(B+C)=4-2 =2 so work done by in A=24/2 =12 day simiarly by B = 24/1 = 24 days.
Finally, LCM for A and B= 24 , unit work for each = 2 and 1.
So total efficency = 1+2 =3 and work done by A+B = 24/3 = 8 DAYS.
(7)
Ivan said:
3 years ago
Thanks for explaining @Parveen Verma.
(1)
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