Time and Work - General Questions (2)

A and B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in :

A.	8 days
B.	10 days
C.	12 days
D.	15 days

Answer: Option C

Explanation:

(A + B)'s 1 day's work =		1	+	1		=	1	.
		15		10			6

Work done by A and B in 2 days =		1	x 2		=	1	.
		6				3

Remaining work =		1 -	1		=	2	.
			3			3

Now,	1	work is done by A in 1 day.
	15

	2	work will be done by a in		15 x	2		= 10 days.
	3				3

Hence, the total time taken = (10 + 2) = 12 days.

10.

A takes twice as much time as B or thrice as much time as C to finish a piece of work. Working together, they can finish the work in 2 days. B can do the work alone in:

A.	4 days
B.	6 days
C.	8 days
D.	12 days

Answer: Option B

Explanation:

Suppose A, B and C take x,	x	and	x	days respectively to finish the work.
	2		3

Then,		1	+	2	+	3		=	1
		x		x		x			2

	6	=	1
	x		2

x = 12.

So, B takes (12/2) = 6 days to finish the work.

11.

Sakshi can do a piece of work in 20 days. Tanya is 25% more efficient than Sakshi. The number of days taken by Tanya to do the same piece of work is:

A.	15
B.	16
C.	18
D.	25

Answer: Option B

Explanation:

Ratio of times taken by Sakshi and Tanya = 125 : 100 = 5 : 4.

Suppose Tanya takes x days to do the work.

5 : 4 :: 20 : x x =		4 x 20
		5

x = 16 days.

Hence, Tanya takes 16 days to complete the work.

12.

A, B and C can complete a piece of work in 24, 6 and 12 days respectively. Working together, they will complete the same work in:

A.	1/24 day
B.	7/24 day
C.	3 3/7 days
D.	4 days

Answer: Option C

Explanation:

Formula: If A can do a piece of work in n days, then A's 1 day's work =	1	.
	n

(A + B + C)'s 1 day's work =		1	+	1	+	1		=	7	.
		24		6		12			24

Formula: If A's 1 day's work =	1	,	then A can finish the work in n days.
	n

So, all the three together will complete the job in		24	days	=	3	3	days.
		7				7

13.

Ravi and Kumar are working on an assignment. Ravi takes 6 hours to type 32 pages on a computer, while Kumar takes 5 hours to type 40 pages. How much time will they take, working together on two different computers to type an assignment of 110 pages?

A.	7 hours 30 minutes
B.	8 hours
C.	8 hours 15 minutes
D.	8 hours 25 minutes

Answer: Option C

Explanation:

Number of pages typed by Ravi in 1 hour =	32	=	16	.
	6		3

Number of pages typed by Kumar in 1 hour =	40	= 8.
	5

Number of pages typed by both in 1 hour =		16	+ 8		=	40	.
		3				3

Time taken by both to type 110 pages =		110 x	3		hours
			40

= 8	1	hours (or) 8 hours 15 minutes.
	4

14.

A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days?

A.	11 days
B.	13 days
C.	20 3/17 days
D.	None of these

Answer: Option B

Explanation:

Ratio of times taken by A and B = 100 : 130 = 10 : 13.

Suppose B takes x days to do the work.

Then, 10 : 13 :: 23 : x x =		23 x 13		x =	299	.
		10			10

A's 1 day's work =	1	;
	23

B's 1 day's work =	10	.
	299

(A + B)'s 1 day's work =		1	+	10		=	23	=	1	.
		23		299			299		13

Therefore, A and B together can complete the work in 13 days.

15.

X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?

A.	6 days
B.	10 days
C.	15 days
D.	20 days

Answer: Option B

Explanation:

Work done by X in 4 days =		1	x 4		=	1	.
		20				5

Remaining work =		1 -	1		=	4	.
			5			5

(X + Y)'s 1 day's work =		1	+	1		=	8	=	2	.
		20		12			60		15

Now,	2	work is done by X and Y in 1 day.
	15

So,	4	work will be done by X and Y in		15	x	4		= 6 days.
	5			2		5

Hence, total time taken = (6 + 4) days = 10 days.

16.

10 women can complete a work in 7 days and 10 children take 14 days to complete the work. How many days will 5 women and 10 children take to complete the work?

A.	3
B.	5
C.	7
D.	Cannot be determined
E.	None of these

Answer: Option C

Explanation:

1 woman's 1 day's work =	1
	70

1 child's 1 day's work =	1
	140

(5 women + 10 children)'s day's work =		5	+	10		=		1	+	1		=	1
		70		140				14		14			7

5 women and 10 children will complete the work in 7 days.

Time and Work - General Questions (2)

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