P is 20% more efficient than Q. If Q alone can finish a work in 10 days, then in how many days will P alone finish the work?

P is 20% more efficient than Q. Time taken by Q = 10 days $\therefore$ Time taken by $\mathrm{P}=\frac{100}{120} \times 10$ $=\frac{25}{3}=8 \frac{1}{3}$ days Alternative: P is 20% more efficient than Q.

According to the question,

6 unit $\rightarrow 10$

1 unit $\rightarrow \frac{10}{6}$

$\therefore 5$ unit $\rightarrow \frac{10}{6} \times 5$

$=8 \frac{1}{3}$ days