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### Discussion :: Time and Work

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 :
2.  A. $$\frac { 1 } { 4 }$$ B. $$\frac { 1 } { 10 }$$ C. $$\frac {7} { 15 }$$ D. $$\frac {8 } { 15 }$$

Answer : Option D

Explanation :

A's 1 day's work =$$\frac { 1 } { 15 };$$

B's 1 day's work =$$\frac { 1 } { 20 };$$

(A + B)'s 1 day's work =$$[\frac { 1 } { 15 }+$$$$\frac { 1 } { 20 }]$$=$$\frac {7} { 60 }$$

(A + B)'s 4 day's work =$$[ \frac {7} { 60 }*4]$$=$$\frac {7} { 15 }$$

Therefore, Remaining work =[1-$$\frac {7} { 15 }$$]=$$\frac {8 } { 15 }$$

Prasad khatua said : (Jun 10, 2021)

I am prepare for job

stephany Buckman said : (Jul 30, 2021)

Where from the 7/60 because I don't understand

Joel Kugonza said : (Jan 01, 2022)

How do they arrive to 7/60 in the first place

Mallikarjun potadar said : (Jan 20, 2022)

How do they substract 1-7/15

renuka said : (Jan 21, 2022)

why cant we take work done by A in 4 DAYS as 4/15 and work done by B in 4 days as 4/20 and add A'S work and B'S work AND THEN SUBTRACT (4/15+4/20 = 2/5) LEFT OVER WORK =1-2/5=3/5