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:
15 days
20 days
25 days
30 days
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 1 of 15.

ESNALA SIDDA said:   1 month ago
A = B+C.
A + B = 1/10,
2B + C = 1/10,
C = 1/50,
B = 1/25,
B = 25hrs.
(8)

K Mohammad Rizwan said:   2 months ago
1/A = 1/B + 1/ C -->1
1/A + I/B = 1/10 -->2
1/C = 1/50 -->3

Subs 1 in 2.

1/B + 1/C + 1/B = 1/10 -->4

Subs 3 in 4.
2/B = 1/10 - 1/50.

2/B = 4/50,
B = 25.
(2)

Prathiba said:   4 months ago
a = b+ c ---> (1)
a+ b = 10 = 1/10 for 1 day work ---> (2)
c = 50 = 1/50 for 1 day work
b = 1/10 - a ---> (3)---from eqn(1)
c = 1/50.
a = b +c ---from (1)
a = 1/10 -a + 1/50 ---from (3)
a = 3/50.
b = 1/10 - a = 1/10 -3/50 = 1/25 .
b = 25 days.
(9)

Julius Openy said:   5 months ago
Given:

A = B + C.
A + B = 10,
C = 50.

Solution :

A + B = 10.
(A + B)'s one day way is 1/10.
A + B = 1/10 ---> 1
from A = B + C ---> 2

Substitute eqn 2 in 1;
B + C + B = 1/10,
2B + 1/50 = 1/10,
2B = 1/10 - 1/50,
2B = 4/50,
B = 1/25.
B alone can do the work in 25 days.
(18)

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.
(1)

VIKRAM said:   6 months ago
Given : AB=10; C=50; find B=?;

LCM of 50, 10 is "50"(total work),
Efficiency of 'AB' =total work : 50/10 = 5,
Efficiency of 'C' =total work : 50/50 = 1.

From efficiency of 'AB & C' is ---> A+B+C : 5 +1 = 6.
Question itself given that : A=B+C;
We know A+B+C = 6--->(1) , in question they said A=B+C -----> (2) ;
Substitute (2) in (1):
We get (1).
B+C+B+C =6;
2B+2C=6; (w.k.t efficiency of C = 1)
2B+2(1)=6;
2B+2=6;
2B=6-2 ; ---> 2B=4; ---> B=2;
Hence, total B alone worked : (50)/2 = '25' days.
(14)

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.
(24)

Patil Pranay said:   1 year ago
A = B + C.
LCM of a+b and c =50,
Efficiency of A+B =5 c=1 than A+B+C=6.

A + B + C = 6 BUT A = B + C
A + A = 6
A = 3.
Then B = 2.

Ans = 50/2 = 25.
(55)

Ani said:   2 years ago
A = B+C,
A+B = 10,
C = 50.


A = B+C=> A = B+1/50.

A+B = 1/10 => B+1/50+B = 1/10.
2B + 1/50 = 1/10.
2B = 4/50.
B = 1/25.
25 DAYS.
(120)

Sudip said:   2 years ago
Short and Simple:

a+b=10, c=50, total work 50.
perday a + b = 5, c = 1.
a+b = 5,
b+c+b = 5,
2b+c = 5,
b = 2/d.
b = 50/2 = 25.
(25)


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