Question

The barrel of a fountain-pen is cylindrical in shape, is $7cm$ long and $5mm$ in diameter. A full barrel of ink in the pen will be used up a writing $330$ words on an average. How many words would use up a bottle of ink containing one fifth of a litre

Answer 1

We have

Volume of barrel $=\pi r^{2}h$

Volume of a barrel $=(\frac{22}{7}\times 0.25\times 0.25\times 7){cm}^3=1.375{cm}^3$

Volume of ink in the bottle $=\frac{1}{5}litre=\frac{1000}{5}{cm}^3=200{cm}^3$

Total number of barrel that can be filled from the given volume of ink $=\frac{200}{1.375}$

So, required number of words $=\frac{200}{1.375}\times 330=48000$