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 will be used up when writing 310 words on an average. How many words would use up a bottle of ink containing one fifth of litre?

The correct answer is: The required number of words is 45091.

Explanations:
Step 1 of 2:
Given, length of the barrel = height of barrel, h  = 7cm
Base radius of the barrel, r = 5/2 mm = 2.5 mm = 0.25cm (since 1cm = 10mm)
Capacity of the barrel = volume of the barrel


 cm³
So, 310 words use up 1.375 cm³ of ink.
Step 2 of 2:
1/5^th of  litre  = 1/51000cm³ = 200cm³
Now, 1.375cm³ of ink is used up by 310 words
 200cm³ of ink will be used up by  = 45090.9  45091 words
Final Answer:
The required number of words is 45091.