Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 7)
7.
A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?
Answer: Option
Explanation:
| A's 1 hour's work = | 1 | ; |
| 4 |
| (B + C)'s 1 hour's work = | 1 | ; |
| 3 |
| (A + C)'s 1 hour's work = | 1 | . |
| 2 |
| (A + B + C)'s 1 hour's work = |  |
1 | + | 1 |  |
= | 7 | . |
| 4 | 3 | 12 |
| B's 1 hour's work = | |
7 | - | 1 | |
= | 1 | . |
| 12 | 2 | 12 |
B alone will take 12 hours to do the work.
Discussion:
97 comments Page 2 of 10.
Vijay said:
1 year ago
(B+C)-(A+C) = (B-A).
(B-A)+(A) = B.
1/3-1/2+1/4= 4/12 - 6/12 + 3/12 = 1/12.
= 12 hrs.
(B-A)+(A) = B.
1/3-1/2+1/4= 4/12 - 6/12 + 3/12 = 1/12.
= 12 hrs.
(6)
Arumugam said:
4 years ago
A = 1/4,
A+b = 1/3.
B = 1/3-1/4 = 1/12.
And = 12.
A+b = 1/3.
B = 1/3-1/4 = 1/12.
And = 12.
(6)
ARAVIND MATHALA said:
1 year ago
A = 1/4
B+C = 1/3
A+C = 1/2
B=?
C = (A+C)-A = > (1/2)-1/4 =>1/4,
B = (B+C)-C = >(1/3)-1/4 =>1/12.
Then B = 12 Hours.
B+C = 1/3
A+C = 1/2
B=?
C = (A+C)-A = > (1/2)-1/4 =>1/4,
B = (B+C)-C = >(1/3)-1/4 =>1/12.
Then B = 12 Hours.
(5)
Soumyaranjan said:
6 years ago
A = 4hrs.
B+C = 3hrs.
A+C = 2hrs.
Work=LCM(4, 3,2) = 12.
The efficiency of A = 12/4 = 3.
The efficiency of BC = 12/3 = 4.
The efficiency of AC = 12/2 = 6.
The efficiency of C = efficiency of (AC-A)
= 6-3 = 3
The efficiency of B = efficiency of (BC-C)
= 4-3 = 1
T = W/E
= 12/1 = 12.
So, B alone will take 12hrs for do it.
B+C = 3hrs.
A+C = 2hrs.
Work=LCM(4, 3,2) = 12.
The efficiency of A = 12/4 = 3.
The efficiency of BC = 12/3 = 4.
The efficiency of AC = 12/2 = 6.
The efficiency of C = efficiency of (AC-A)
= 6-3 = 3
The efficiency of B = efficiency of (BC-C)
= 4-3 = 1
T = W/E
= 12/1 = 12.
So, B alone will take 12hrs for do it.
(3)
Aman Jadhao said:
4 years ago
Hi;
a=4h
B+c=3h
A+c=2h
B=?.
A b+c. A+c
4. 3 2
Take LCM of
Lcm=12
After LCM value is
3. 4. 6.
Adding the value we get
A + c = 2
C = 1.
Then solve
B+c =4,
B=3.
Simply multiple with LCM values of b&c
3 * 4 = 12 hours.
a=4h
B+c=3h
A+c=2h
B=?.
A b+c. A+c
4. 3 2
Take LCM of
Lcm=12
After LCM value is
3. 4. 6.
Adding the value we get
A + c = 2
C = 1.
Then solve
B+c =4,
B=3.
Simply multiple with LCM values of b&c
3 * 4 = 12 hours.
(3)
Spoorti said:
4 years ago
Thank you @Bhanu.
(3)
Logesh said:
4 years ago
Simply, subs A's value in Eqn 1:
A + C= 1/2
C = 1/2-1/4
C = 1/4
Sub C's VALUE IN B+C = 1/3;
B = 1/3-1/4
B = 1/12 , we got it.
A + C= 1/2
C = 1/2-1/4
C = 1/4
Sub C's VALUE IN B+C = 1/3;
B = 1/3-1/4
B = 1/12 , we got it.
(2)
ESNALA SIDDA said:
2 months ago
A = 1/4.
B + C = 1/3.
A + C = 1/2.
C = 1/2-1/4.
= 1/4,
B = 1/3 - 1/4.
= 1/12.
=12hrs.
B + C = 1/3.
A + C = 1/2.
C = 1/2-1/4.
= 1/4,
B = 1/3 - 1/4.
= 1/12.
=12hrs.
(2)
Xyx said:
8 years ago
How it will 7/12-1/2=1/12?
(1)
Bits said:
8 years ago
A in 4hrs.
B+C _ 3.
A+C _ 2.
Total work by taking lcm of 4,3,2 is 12units.
A in one day do = 12/4= 3.
A+C_ 6.
So C=3.
In the same way,
B+C= 12/3 > 4.
So B=1.
At last B =12/1=12. That's the answer!.
B+C _ 3.
A+C _ 2.
Total work by taking lcm of 4,3,2 is 12units.
A in one day do = 12/4= 3.
A+C_ 6.
So C=3.
In the same way,
B+C= 12/3 > 4.
So B=1.
At last B =12/1=12. That's the answer!.
(1)
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