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

Let us first calculate the volume of barrel of pen that is of cylindrical shape

Consider barrel,

Since 1 cm = 10 mm

Base diameter = 5 mm = 0.5 cm

Base radius, r = 0.25 cm

Height, h = 7 cm

We know that,

Volume of a cylinder = πr²h

Volume of barrel = π(0.25)²7

Volume of barrel = `22/7 xx 0.25 xx 0.25 xx 7` = 1.375 cm³

Hence, according to the question,

1.375 cm³ of ink can write 3300 words

No of words that can be written by 1 cm³ of ink = `3300/1.375` = 2400 words

1/5^th of a liter = 0.2L

We know that,

1L = 1000 cm³

0.2L = 200 cm³

So, no of words that can be written by 200 cm³ = 2400(200) = 480000 words

Therefore, 1/5^th of a liter ink can write 480000 words.