86. A can complete a work in 6 days while B can complete the same work in 12 days. If they work together and complete it, the portion of the work done by A is

1. 1. 1

      3

   
   
   

   2. 2

      3

   
   
   

   3. 1

      4

   
   
   

   4. 1

      2

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using basics of Rule 2,
   Time taken by A and B
   

   =	6 × 12	=	6 × 12	= 4
   	6 + 12		18

   
   ∴ Work done by A in 4 days
   

   =	4	=	2
   	6		3

   Correct Option: B

   Using basics of Rule 2,
   Time taken by A and B
   

   =	6 × 12	=	6 × 12	= 4
   	6 + 12		18

   
   ∴ Work done by A in 4 days
   

   =	4	=	2
   	6		3

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87. A does 7/10 part of work in 15 days. After that he completes the remaining work in 4 days with the help of B. In how many days will A and B together do the same work ?

1. 1. 10	1	days
      	3

   
   
   

   2. 12	2	days
      	3

   
   
   

   3. 13	1	days
      	3

   
   
   

   4. 8	1	days
      	4

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using basics of Rule 2,
   Remaining work
   

   = 1 -	7	=	3
   	10		10

   
   

   ∵ (A + B) take 4 days to do	3	work
   	10

   
   ∴ (A + B) will do the work in
   

   4 ×	10	days
   	3

   
   

   =	40	= 13	1	days
   	3		3

   Correct Option: C

   Using basics of Rule 2,
   Remaining work
   

   = 1 -	7	=	3
   	10		10

   
   

   ∵ (A + B) take 4 days to do	3	work
   	10

   
   ∴ (A + B) will do the work in
   

   4 ×	10	days
   	3

   
   

   =	40	= 13	1	days
   	3		3

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88. A can finish a work in 18 days and B can do the same work in half the time taken by A. Then working together what part of the same work they can finish in a day ?

1. 1. 1

      6

   
   
   

   2. 2

      5

   
   
   

   3. 1

      9

   
   
   

   4. 2

      7

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using basics of Rule 2,
   

   A’s 1 day’s work =	1
   	18

   
   

   B’s 1 day’s work =	1
   	9

   
   ∴ (A + B)’s 1 day’s work
   

   =	1	+	1	=	1 + 3	=	1
   	18		9		18		6

   Correct Option: A

   Using basics of Rule 2,
   

   A’s 1 day’s work =	1
   	18

   
   

   B’s 1 day’s work =	1
   	9

   
   ∴ (A + B)’s 1 day’s work
   

   =	1	+	1	=	1 + 3	=	1
   	18		9		18		6

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89. A does 4/5 of a piece of work in 20 days; He then calls in B and they finish the remaining work in 3 days. How long B alone will take to do whole work ?

1. 1. 37	1	days
      	2

   
   
   

   2. 37 days

   
   
   

   3. 40 days

   
   
   

   4. 23 days

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using basics of Rule 2,
   A can do the whole work in
   

   =	20 × 5	= 25 days
   	4

   
   

   Remaining work = 1 -	4	=	1
   	5		5

   
   

   ∴ (A + B)’s 1 day’s work =	1
   	15

   
   

   and A’s 1 day’s work =	1
   	25

   
   ∴ B’s 1 day’s work
   

   =	1	-	1	=	5 - 3	=	2
   	15		25		75		75

   
   

   ∴ B can finish the work in	75	days
   	2

   
   

   i.e. 37	1	days
   	2

   Correct Option: A

   Using basics of Rule 2,
   A can do the whole work in
   

   =	20 × 5	= 25 days
   	4

   
   

   Remaining work = 1 -	4	=	1
   	5		5

   
   

   ∴ (A + B)’s 1 day’s work =	1
   	15

   
   

   and A’s 1 day’s work =	1
   	25

   
   ∴ B’s 1 day’s work
   

   =	1	-	1	=	5 - 3	=	2
   	15		25		75		75

   
   

   ∴ B can finish the work in	75	days
   	2

   
   

   i.e. 37	1	days
   	2

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90. A can cultivate 2/5 th of a land in 6 days and B can cultivate 1/3 rd of the same land in 10 days. Working together A and B can cultivate 4/5 th of the land in:

1. 1. 4 days

   
   
   

   2. 5 days

   
   
   

   3. 8 days

   
   
   

   4. 10 days

   
   
   

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1. View Hint View Answer Discuss in Forum

   Using basics of Rule 2,
   The part of field cultivated by A in 1 day
   

   =	2	=	1
   	5 × 6		15

   
   The part of field cultivated by B in 1 day
   

   =	1	=	1
   	3 × 10		30

   
   ∴ The part of field cultivated by A and B together
   

   =	1	+	1	=	3	=	1
   	15		30		30		10

   
   ∴ 4/5 part of field cultivated by A and B together in
   

   =	4	×	10	days
   	5		1

   
   

   =	40	= 8 days
   	5

   Correct Option: C

   Using basics of Rule 2,
   The part of field cultivated by A in 1 day
   

   =	2	=	1
   	5 × 6		15

   
   The part of field cultivated by B in 1 day
   

   =	1	=	1
   	3 × 10		30

   
   ∴ The part of field cultivated by A and B together
   

   =	1	+	1	=	3	=	1
   	15		30		30		10

   
   ∴ 4/5 part of field cultivated by A and B together in
   

   =	4	×	10	days
   	5		1

   
   

   =	40	= 8 days
   	5

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