15. A and B can do a piece of
work in 15 days and 20 days
respectively. Find the number
of days that B will take to
complete remaining work ,if A
worked for 3 days and left. *
Answers
Answer:
A can do a work in 15 days and B in 20 days. If they work together for 4 days then what is the fraction of work that is left?
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Take LCM of 15 and 20 as the total amount of work which is 60 units in this case.
A can do work in 15 days therefore amount of work done by A in 1 day is 60/15 = 4 units
B can do work in 15 days therefore amount of work done by A in 1 day is 60/20 = 3 units
Total amount of work done in 1 day =A work of 1 day+B's work of 1 day=4 units +3 units=7 units
Amount of work done in 4 days =4*7=28 units
Amount of Work Left = 60–28=32 units
Fraction of work left = Amount of work left/ Total Work = 32/60 = 8/15.
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A can do a work in 15 days and B in 20 days
A can do the work in 15 days.
Thus A finishes in one day = 1/15 work.
B finishes in one day = 1/20 work
Together, they finishes in one day
1/15 + 1/20 =7/60 work
If they work together for 4 days then what is the fraction of work that is left?
In 4 days they will finish work = 4 × 7/60 = 7/15 work
Remaining work left = 1 - 7/15
= (15 - 7)/15
= 8/15
The fraction of work left is 8/15
Step-by-step explanation:
Take LCM of 15 and 20 as the total amount of work which is 60 units in this case.
A can do work in 15 days therefore amount of work done by A in 1 day is 60/15 = 4 units
B can do work in 15 days therefore amount of work done by A in 1 day is 60/20 = 3 units
Total amount of work done in 1 day =A work of 1 day+B's work of 1 day=4 units +3 units=7 units
Amount of work done in 4 days =4*7=28 units
Amount of Work Left = 60–28=32 units
Fraction of work left = Amount of work left/ Total Work = 32/60 = 8/15.