Question

A and B work together, but a leaves the job after 2 days, how much of the work is the left than

Answer 1

1st Method:

(A+B)'s one day's work = 1/3 part;
(A+B) works 2 days together = 2/3 part;
Remaining work = 1-(2/3) = 1/3 part;
1/3 part of work is completed by A in two days;
Hence, one day's work of A = 1/6;
Then, one day's work of B = 1/3-1/6=1/6;
So, B alone can complete the whole work in 6 days.
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2nd method:
(A+B)'s one day's % work = 100/3 = 33.3%
Work completed in 2 days = 66.6%
Remaining work = 33.4%;
One day's % work of A = 33.4/2 = 16.7%;
One day's work of B = 33.3 - 16.7 = 16.7%;
B alone can complete the work in,
= 100/16.7 = 6 days.