Percentage Problem 15

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A can do a piece of work in 20 days. B is found to be 25 % more efficient than A.
Find in how many days will : (i) B do the work? (ii) A and B will do the work together?

Solution: (i) Since, A can do the work in 20 days

his one day work = 1 / 20

Given, B is 25 % more efficient than A

=> B's one day work = 1 / 20 + 25 % of 1 / 20

= 1 / 20 + 25 / 100 X 1 / 20 = 1 / 20 + 1 / 80 = 5 / 80 = 1 / 16

Therefore, B will do the work in 16 days

(ii) Since, (A + B)'s one day's work = 1 / 20 + 1 / 16 = (4 + 5) / 80 = 9 / 80

Therefore, A and B together will do the work in 80 / 9 days = 8-8/9 days

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