Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 8)
8.
A can do a certain work in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in:
Answer: Option
Explanation:
| (A + B)'s 1 day's work = | 1 |
| 10 |
| C's 1 day's work = | 1 |
| 50 |
| (A + B + C)'s 1 day's work = |  |
1 | + | 1 |  |
= | 6 | = | 3 | . .... (i) |
| 10 | 50 | 50 | 25 |
A's 1 day's work = (B + C)'s 1 day's work .... (ii)
| From (i) and (ii), we get: 2 x (A's 1 day's work) = | 3 |
| 25 |
 A's 1 day's work = |
3 | . |
| 50 |
 B's 1 day's work |
|
1 | - | 3 | |
= | 2 | = | 1 | . |
| 10 | 50 | 50 | 25 |
So, B alone could do the work in 25 days.
Discussion:
146 comments Page 6 of 15.
Devesh said:
7 years ago
1/A+1/B=1/10 ------------> 1
GIVEN
1/A = 1/B + 1/C -------------> 2
1/A-1/B = 1/C from eq2.
1/A-1/B = 1/50.
Now solve 1 and
1/A=6/100 put this value in eqn 1.
We get 1/B = 4/100.
So, B can do in 25 days.
GIVEN
1/A = 1/B + 1/C -------------> 2
1/A-1/B = 1/C from eq2.
1/A-1/B = 1/50.
Now solve 1 and
1/A=6/100 put this value in eqn 1.
We get 1/B = 4/100.
So, B can do in 25 days.
Alok said:
1 decade ago
a = b+c....(i).
a+b = 1/10 (given).
a-b = c.
a-b = 1/50 (c alone can do work in 50 days putting the value of c here)....(ii).
Solving I and II.
a = 1/30.
b = 1/10-1/30.
c = 1/15.
How this one is wrong?
a+b = 1/10 (given).
a-b = c.
a-b = 1/50 (c alone can do work in 50 days putting the value of c here)....(ii).
Solving I and II.
a = 1/30.
b = 1/10-1/30.
c = 1/15.
How this one is wrong?
Anandhan said:
1 decade ago
a = a+b;
a+b = 1/10; together;-----------(1).
c = 1/50;
Take 1st equation,
a+b=1/10;
we know a = b+c; so substitute,
b+c+b=1/10;
2b+1/50=1/10;
2b=1/10-1/50;
2b=4/50;
b=4/100;
b=2/50;
b=25;
Thats it.
a+b = 1/10; together;-----------(1).
c = 1/50;
Take 1st equation,
a+b=1/10;
we know a = b+c; so substitute,
b+c+b=1/10;
2b+1/50=1/10;
2b=1/10-1/50;
2b=4/50;
b=4/100;
b=2/50;
b=25;
Thats it.
Anchal said:
1 decade ago
Best method is Awoke method, because this is shortcut for doing in competative exams. But for understandin the solution, we can see Nagu's method.
So good job have done by both the guys. Thankyou.
So good job have done by both the guys. Thankyou.
Kingsley said:
6 years ago
Easiest method:
A = B+C ---> (1)
A+B = 1/10 ---> (2)
C=1/50 ---> (3).
From (2) A = 1/10-B.
By substituting (2) & (3) in (1), we get;
1/10-B = B + 1/50.
Solving for B.
2B = 1/10 - 1/50 = 1/25.
A = B+C ---> (1)
A+B = 1/10 ---> (2)
C=1/50 ---> (3).
From (2) A = 1/10-B.
By substituting (2) & (3) in (1), we get;
1/10-B = B + 1/50.
Solving for B.
2B = 1/10 - 1/50 = 1/25.
(2)
DHARMENDRA said:
1 decade ago
A=B+C-----------------(1)
A+B=1/10--------------(2)
C=1/50----------------(3)
(1)+(2)
(B+C)+B=1/10-----------(4)
(3)+(4)
B+(1/50)+B=1/10
2B=(1/10)-(1/50)
B=1/25
SO B COMPLETE THE TASK IN 25 DAYS
A+B=1/10--------------(2)
C=1/50----------------(3)
(1)+(2)
(B+C)+B=1/10-----------(4)
(3)+(4)
B+(1/50)+B=1/10
2B=(1/10)-(1/50)
B=1/25
SO B COMPLETE THE TASK IN 25 DAYS
MONISH said:
6 years ago
We know A+B= 10 ----> 1
C=10 ----> 2
GIVEN;
A=B+C ----> 3.
JUST PUT 3, 2 IN 1
B + C + B = 10
2B + 60 = 10
B = -50/2
B = 25 (IT BECAME POSITIVE BECAUSE DAY IS NOT In NEGATIVE).
C=10 ----> 2
GIVEN;
A=B+C ----> 3.
JUST PUT 3, 2 IN 1
B + C + B = 10
2B + 60 = 10
B = -50/2
B = 25 (IT BECAME POSITIVE BECAUSE DAY IS NOT In NEGATIVE).
Kayden break said:
5 months ago
1/A + 1/B = 1/10
As A and B + C IS SAME
1/A = 1/B+1/C. (1/C=1/50 AS GIVEN IN QUES)
Equate both equations
1/A + 1/B = 1/10.
(1/B + 1/C) + 1/B = 1/10,
2/B + 1/50 = 1/10,
B = 25.
As A and B + C IS SAME
1/A = 1/B+1/C. (1/C=1/50 AS GIVEN IN QUES)
Equate both equations
1/A + 1/B = 1/10.
(1/B + 1/C) + 1/B = 1/10,
2/B + 1/50 = 1/10,
B = 25.
(1)
VRAJ said:
1 decade ago
A = B+C.
A+B = 10.
C = 50.
A+B+C = 1/10+1/50.
A+A = 1/10+1/50.
2A = 6/50.
A = 3/50.
A = B+C.
3/50 = B+1/50.
B = 3/50-1/50.
B = 2/50.
B = 1/25.
B CAN DONE THE WORK IN 25 DAYS.
A+B = 10.
C = 50.
A+B+C = 1/10+1/50.
A+A = 1/10+1/50.
2A = 6/50.
A = 3/50.
A = B+C.
3/50 = B+1/50.
B = 3/50-1/50.
B = 2/50.
B = 1/25.
B CAN DONE THE WORK IN 25 DAYS.
Subhash said:
11 months ago
A = B + C.
Lcm of 10 and 50 = 50 ( Total Work)
Eff of A + B = 5 --->1.
Eff of C = 1.
A = 5- B from 1.
A = B + C.
5 - B = B + 1.
B = 2.
Time= TW/Eff of B.
= 50/2 = 25.
Lcm of 10 and 50 = 50 ( Total Work)
Eff of A + B = 5 --->1.
Eff of C = 1.
A = 5- B from 1.
A = B + C.
5 - B = B + 1.
B = 2.
Time= TW/Eff of B.
= 50/2 = 25.
(24)
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