The maximum speed of a boat in still water is 27 km / h. Now this boat is moving downstream in a river flowing at 9 km / h. A man in the boat throws…

The maximum speed of a boat in still water is $\displaystyle 27 \mathrm{~km} / \mathrm{h}$. Now this boat is moving downstream in a river flowing at $\displaystyle 9 \mathrm{~km} / \mathrm{h}$. A man in the boat throws a ball vertically upwards with speed of $\displaystyle 10$ m/s. Range of the ball as observed by an observer at rest on the river bank, is $\displaystyle \_\_\_\_$ cm. (Take $\displaystyle \mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$ )