If Anil does 40% of certain work and Sunil the remaining, it takes 41 days to complete the work but when Sunil does 65% of the same work and Anil the remaining, it takes 41½ days to finish the work. Anil is more efficient than Sunil by
Working individually, let Anil and Sunil takes x and y days respectively.
Then Anil's 1 day work=1/x and Sunil's 1 day work=1/y
As per given conditions: (40/100) / (1/x) + (60/100) / (1/y) = 41
⇒ 2x + 3y = 205 ---(i)
And (65/100) / (1/y) + (35/100) / (1/x) = 83/2
⇒ 7x + 13y = 830 ---(ii)
Solving Eqn (i) & (ii), we get x=35, y=45
Efficiency of work of Anil and Sunil = 1/35 : 1/45 = 9 : 7
.'. % Anil is more efficient than Sunil = [(9-7)/7]*100 = 28.57%
Correct Option 8)