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:
100 comments Page 1 of 10.
A K BURNWAL said:
5 days ago
A- 4 hours, a's 1 hour = 1/4.
B + C- 3 hours, B + C's 1 hour = 1/3,
A + C- 2 hours, A + C'1 hour = 1/2,
C's 1 hour = 1/2 - 1/4 = 1/4.
B = 1/3 - 1/4 = 1/12.
So, B takes 12 hours to complete work.
B + C- 3 hours, B + C's 1 hour = 1/3,
A + C- 2 hours, A + C'1 hour = 1/2,
C's 1 hour = 1/2 - 1/4 = 1/4.
B = 1/3 - 1/4 = 1/12.
So, B takes 12 hours to complete work.
Gayathri said:
1 week ago
A = 1/4
B + C = 1/3 ----> eq(1)
A + C = 1/2 ----> eq(2)
Sub eq(1)-eq(2).
B + C - A - C = 1/3 - 1/2,
B - A = -1/6,
B = -1/6 + 1/4( where A=1/4).
B = 1/12.
Hence B alone takes 12 hours.
B + C = 1/3 ----> eq(1)
A + C = 1/2 ----> eq(2)
Sub eq(1)-eq(2).
B + C - A - C = 1/3 - 1/2,
B - A = -1/6,
B = -1/6 + 1/4( where A=1/4).
B = 1/12.
Hence B alone takes 12 hours.
Komal pal said:
8 months ago
A = 4.
B + C = 3.
A + C = 2.
FIND THE LCM. 4,3,2=12
A = 3
B + C = 4.
A + C = 6.
Then;
A + C
3 + C = 6.
C = 6 - 3,
C = 3.
B + C = 4.
B + 3 = 4.
B = 4 - 3,
B = 1.
12/1=12
B + C = 3.
A + C = 2.
FIND THE LCM. 4,3,2=12
A = 3
B + C = 4.
A + C = 6.
Then;
A + C
3 + C = 6.
C = 6 - 3,
C = 3.
B + C = 4.
B + 3 = 4.
B = 4 - 3,
B = 1.
12/1=12
(14)
Kavit vaishnav said:
11 months ago
A takes 4 hours, 1 hour work = 25%.
For A+C = 2 hours =100% work.
A's part = 50%(for 2 hours),
Remaining part done by C 50% in time 2 hours. So C also does 25% in 1 hour.
Now B+C = 3 Hours = 100% work.
C's part = 3*25% = 75% in 3 hours.
B's part = remaining work = 25% in 3 hours.
So, B' s efficiency = 100% in 12 hours.
For A+C = 2 hours =100% work.
A's part = 50%(for 2 hours),
Remaining part done by C 50% in time 2 hours. So C also does 25% in 1 hour.
Now B+C = 3 Hours = 100% work.
C's part = 3*25% = 75% in 3 hours.
B's part = remaining work = 25% in 3 hours.
So, B' s efficiency = 100% in 12 hours.
(1)
ESNALA SIDDA said:
1 year 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.
(8)
Lakshmi said:
2 years ago
A --->1/4.
A+B -->1/3.
(A+B)-A -->1/3-1/4.
= 1/12.
B alone 12 hours.
A+B -->1/3.
(A+B)-A -->1/3-1/4.
= 1/12.
B alone 12 hours.
(22)
SUREKHA said:
2 years ago
A = 1/4
B + C = 1/3
A+C = 1/2
B =?
A + (B + C) - (A + C) = 1/4 + 1/3 - 1/2
B = 1/12.
B = 12 DAYS.
B + C = 1/3
A+C = 1/2
B =?
A + (B + C) - (A + C) = 1/4 + 1/3 - 1/2
B = 1/12.
B = 12 DAYS.
(24)
Kumar Pawar said:
2 years ago
A = 1/4 ---> (1)
B + C = 1/3 ---->(2)
A + C = 1/2---->(3)
Put Equation in (1)in (3)
A + C = 1/2.
1/4 + C = 1/2,
C = 1/2 - 1/4 = 1/4.
C = 1/4.
Put C in equation (2).
B + 1/4 = 1/3
B = 1/3 - 1/4
B = 1/12 Days.
So, the Answer is 12 days.
B + C = 1/3 ---->(2)
A + C = 1/2---->(3)
Put Equation in (1)in (3)
A + C = 1/2.
1/4 + C = 1/2,
C = 1/2 - 1/4 = 1/4.
C = 1/4.
Put C in equation (2).
B + 1/4 = 1/3
B = 1/3 - 1/4
B = 1/12 Days.
So, the Answer is 12 days.
(17)
Moustafa Elhosiny said:
2 years ago
A's 1 hour = 1/4,
B+C 1 hour = 1/3,
A+C 1 hour = 1/2.
C = 1/2 - A
C = 1/2 - 1/4 = 1/4.
B+C = 1/3,
Then B = 1/3 -C.
B = 1/3 - 1/4 = 1/12.
So, B can do the work in 12 hours.
B+C 1 hour = 1/3,
A+C 1 hour = 1/2.
C = 1/2 - A
C = 1/2 - 1/4 = 1/4.
B+C = 1/3,
Then B = 1/3 -C.
B = 1/3 - 1/4 = 1/12.
So, B can do the work in 12 hours.
(8)
ARAVIND MATHALA said:
2 years 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)
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