Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 26)

Time and Work

26.

A and B can do a work in 8 days, B and C can do the same work in 12 days. A, B and C together can finish it in 6 days. A and C together will do it in :

4 days

6 days

8 days

12 days

Answer: Option

Explanation:

(A + B + C)'s 1 day's work =	1	;
	6

(A + B)'s 1 day's work =	1	;
	8

(B + C)'s 1 day's work =	1	.
	12

(A + C)'s 1 day's work

=		2 x	1		-		1	+	1
			6				8		12

=		1	-	5
		3		24

=	3
	24

=	1	.
	8

So, A and C together will do the work in 8 days.

Discussion:

53 comments Page 2 of 6.

PRASHANT VERMA said: 6 years ago

1/8+1/12-1/6=1/24.

BECAUSE A+B = 8
B+C = 12
A+C = ?
A+B+C = 6.

Rehan said: 6 years ago

(A+B)+(B+C)+(C+A) = 2 (A+B+C).
1/8 + 1/12+ (C+A) = 2 * 1/6.

Vishal sinha said: 6 years ago

It can be done in a much simpler way.

(A+B)'s 1-day work = 1/8.
(B+C)'s 1-day work = 1/12.

(A+B)+(B+C)'s 1 day work= 1/8+1/12.
B+(A+B+C)=5/24,
B=5/24-1/6,
B=1/24.

So, A+B+C=1/6,
Putting the value of B.

(A+C)'s 1 day work = 1/6 - 1/24 = 1/8.

Time taken = 8 days.

Ricky nahar said: 7 years ago

@Nandhu.

Why a=2?

Nav said: 7 years ago

Why can't we simply subtract A+B's 1-day work from B+C's 1-day work to get A+C's 1-day work?

Rohit kushwaha said: 7 years ago

Thank you @Bhanu.

Chary said: 7 years ago

good explanation, thanks all.

Santosh said: 7 years ago

A+B ....8 DAY- 3unit. L.C.M-24 UNIT
B+C......12 DAY - 2 unit.
A+B+C......6 DAY -(24/6)...4 unit .

Then,
A+B+C=4. A+B=3....(3+C=4 =C=1)
C=1.
B+C=2 UNIT .....C=1.
B=1.
A+B=3.
B=1.
A=2 .
A and c's work.
A+c=2+1=3 unit per day,
Total work =24 unit,
A+c=24/3=8 day.

Deep said: 7 years ago

Thanks @Parveen.

Vikas said: 8 years ago

Thanks for the explanation.

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