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 10 of 15.

ALOK URMALIYA said:   9 years ago
A = B + C
A + B = 1/10.
C = 1/50.

(A + B - A) = B.
(1/10 - B - 1/50) = B.
4/50 = 2B.
4/100 = B.
B =1/25.

Bala said:   7 years ago
A=B+C;
IF A+B=1/10,
then.

(B+C)+B=1/10,
c=1/50,
2B+C=1/10,
2B+1/50=1/10,
2B=1/10-1/50,
2B=2/25,

B=1/25.

Hilal said:   1 decade ago
B's work=x
C's work=y
hence A's work=x+y
A and B together work= 2x+y
given y=1/50
substituting x=1/25

Sudhakar said:   1 decade ago
a=b+c............(1).
a+b=1/10.
c=1/50.
From (1),
[(1/10)-b=b+(1/50)].
2b=4/50.
b=1/25.
25 days.

Nikhil said:   1 decade ago
Mr.Awoke your method is awesome and moreover its applicable to all such type of probs...thanks!

GAURAV said:   1 decade ago
A = B+C => A-B = C.

A+B = 1/10.

C = 1/50.

=> A-B = 1/50.

Solving eqns we get B = 25.

Sisindri said:   6 years ago
A = b+c.

A+b = 1/10,c=1/50
B+C+B = 1/10.

2b = (1/10)-(1/50).
2b = 2/25,
b = 1/25,
So,b = 25.
(1)

Payal said:   8 years ago
B= x days
C = y days
A = x+y days
given: y= 50
& A +B = x+x+y = 2x+y=10.
=>x= 20 ans.

Suresh said:   1 decade ago
a+b = 1/10.
a = b+c eq.1.
c = 1/50.

Then a-b = 1/50 eq.2.
Solving 1 and 2 we get b = 1/25.

Akshay Jaywant said:   9 years ago
10(A + B) = 50 C.
(B + C + B) = 5C.
2B = 4C.
B = 2C.

Therefore, B = 50/2 = 25 days.


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