Question

The barrel of a fountain pen, cylindrical in shape, is 7 cm long and 5 mm in diameter. A full

barrel of ink in the pen is used up on writing 3300 words on an average. How many words can
be written in a bottle of ink containing one fifth of a litre?​

Answer 1

480,000 words

Explanation:

For barrel of pen:

h = 7 cm, d = 5 mm

r = 5/2 = 2.5 mm = 0.25 cm

`Volume \: of \: barrel = \pi {r}^(2) h \\ \\ = (22)/(7) * {(0.25)}^(2) * 7 \\ \\ = 22 * 0.0625 \\ \\ = 1.375 \: {cm}^(3) \\ \\ one \: fifth \: of \: a \: litre \\ = (1)/(5) * 1000 \: ml \\ \\ = 200 \: ml \\ \\ = 200 \: {cm}^(3) \\ \\ no \: of \: words = (3300 * 200)/(1.375) \\ \\ = (660000)/(1.375) \\ \\ = 480,000 \\`