TIME AND WORK

1. TIME AND WORK
   
   
   1.Work from Days:

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

2. Days from Work:

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

3. Ratio:
   If A is thrice as good a workman as B, then:
   Ratio of work done by A and B = 3 : 1.
   Ratio of times taken by A and B to finish a work = 1 : 3.
   EXAMPLES
   1.A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
   
   

   a) 1/4        b)1/10        c)7/15      d)8/15

   
   Answer: Option d
   
   Explanation:

   A's 1 day's work =	1	;
   	15

   B's 1 day's work =	1	;
   	20

   (A + B)'s 1 day's work =		1	+	1		=	7	.
   		15		20			60

   (A + B)'s 4 day's work =		7	x 4		=	7	.
   		60				15

   Therefore, Remaining work =		1 -	7		=	8	.
   			15			15