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

A 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 a litre?

Given, diameter of cylindrical barrel = 5 mm
∴ Radius of cylindrical barrel,
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