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 6 of 10.
Sonu said:
1 decade ago
A=1/4
B+C=1/3
A+C=1/2
----------(subtracting on both sides)
B-A=(-)1/6
B=(- 1/6)+(1/4)
B=1/12
Therefore, 12 hours!!!!
B+C=1/3
A+C=1/2
----------(subtracting on both sides)
B-A=(-)1/6
B=(- 1/6)+(1/4)
B=1/12
Therefore, 12 hours!!!!
Dharam Verma said:
1 decade ago
A's 1 day work = 1/4
(B+C)'s 1 day work = 1/3
(A+C)'s 1 day work = 1/2
So, C's 1 day work = (A+C)'s 1 day work - A's 1 day work
= 1/2 - 1/4
= 1/4
Now, B's 1 day work = (B+C)'s 1 day work - C's 1 day work
= 1/3 - 1/4
= 1/12 (taking LCM)
So, B complete the work in = 12 days.
(B+C)'s 1 day work = 1/3
(A+C)'s 1 day work = 1/2
So, C's 1 day work = (A+C)'s 1 day work - A's 1 day work
= 1/2 - 1/4
= 1/4
Now, B's 1 day work = (B+C)'s 1 day work - C's 1 day work
= 1/3 - 1/4
= 1/12 (taking LCM)
So, B complete the work in = 12 days.
Sainath said:
1 decade ago
a=1/4
a+c=1/2
c=1/2-a
c=1/4
: b+c=1/3
b=1/3-c
b=1/12
b can do it in 12 days....
a+c=1/2
c=1/2-a
c=1/4
: b+c=1/3
b=1/3-c
b=1/12
b can do it in 12 days....
Decoder said:
1 decade ago
What is wrong with this approach :
C 's 1 hour work=(A+C)'s 1 hour work -A 's 1 hour work=1/2
then B's i hour work = (B+C)'s 1 hour work-C's 1 hour work =1/6
But the answer as mentioned with another approach is 1/12
Can anybody explain ?
C 's 1 hour work=(A+C)'s 1 hour work -A 's 1 hour work=1/2
then B's i hour work = (B+C)'s 1 hour work-C's 1 hour work =1/6
But the answer as mentioned with another approach is 1/12
Can anybody explain ?
Sireesha said:
1 decade ago
[(b+c)=1/3]-[(a+c)=1/2]
=> b=1/12
=>b's time= 12hrs
=> b=1/12
=>b's time= 12hrs
Kumar said:
1 decade ago
A =1/4 (A's ONE HOUR WORK)
B+C =1/3 (B+C's ONE HOUR WORK)
A+C =1/2 (A+C's ONE HOUR WORK)
C =1/2-A
B+1/2-1/4=1/3 (submitting c value in b+c=1/3 for value of b)
B=1/3-1/2+1/4
B=1/12
B+C =1/3 (B+C's ONE HOUR WORK)
A+C =1/2 (A+C's ONE HOUR WORK)
C =1/2-A
B+1/2-1/4=1/3 (submitting c value in b+c=1/3 for value of b)
B=1/3-1/2+1/4
B=1/12
Arun said:
1 decade ago
Just simply i know that A's is 1/4
B+C is 1/3
So do it
1/3 - 1/4
And u get 1/12
B's work 12 hour
B+C is 1/3
So do it
1/3 - 1/4
And u get 1/12
B's work 12 hour
Aditya said:
1 decade ago
The above methods are enough to solve this problem...but when i got this question i thought to convert all hours into days...although its a very time consuming...but i got the answer...i am just a beginner...so satisfied with it
1 day=24 hours
1/24 day=1 hour
i/6 day=4 hour....i hope you got my point...but its time consuming so don't use this method...i shared it because...i want to tell you ...what strikes on my mind.
1 day=24 hours
1/24 day=1 hour
i/6 day=4 hour....i hope you got my point...but its time consuming so don't use this method...i shared it because...i want to tell you ...what strikes on my mind.
Shro said:
1 decade ago
Thanku hindu:).
Rajin said:
1 decade ago
A = 1/4
B+C = 1/3
A+C = 1/2
A+B+C = 1/4+ 1/3 = 7/12
TO FIND B'W WORK
A+B+C - (A+C) = 7/12 - 1/2 = 1/12
B+C = 1/3
A+C = 1/2
A+B+C = 1/4+ 1/3 = 7/12
TO FIND B'W WORK
A+B+C - (A+C) = 7/12 - 1/2 = 1/12
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers