## 236. Math Puzzle $1 / 85$

A well has four inflows. The first fills the well in 6 hours, i.e., 1/6 fill per hour, the second in 48 hours, the third in 72 hours, and the fourth in 96 hours. In how many hours will the well be full if all inflows are operating simultaneously?
The well would be filled after $4.72 \mathrm{~h}$. or $4 \mathrm{~h} 43 \mathrm{~min}$.

Solution path: $\frac{x}{6}+\frac{x}{48}+\frac{x}{72}+\frac{x}{96}=1$

$x$ is the time sought; 1 is the number of fillings; the least common denominator is 288