Management Aptitude Test Sep 2013 Paper

(c) Usha takes 25 days to complete a work.
Then time taken by Asha will be 25 - 25% of 25
25 - $\frac{25\times 25}{100}$
25 - $\frac{25}{4}=\frac{75}{4}$ days
Let total time taken to finish the work be x days
Then, by given condition,
$\frac{4}{75}\mathit{x}+\frac{5}{25}$ = 1
$\frac{4\mathit{x}+15}{75}$ = 1
4x = 75 - 15
x = $\frac{60}{4}$ = 15 days
∴ Number of days for which Asha worked alone = (15 - 5) = 10 days