ML Aggarwal Solutions Class 10 Mathematics Solutions for Mensuration Exercise 17.1 in Chapter 17 - Mensuration

Question 15 Mensuration Exercise 17.1

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 a litre?

Answer correct to the nearest. 100 words.



The capacity of a cylinder is measured by its volume, which determines how much material it can carry.

Height of the barrel of a pen, h = 7 cm

Diameter, d = 5mm = 0.5 cm

Radius, r = d/2 = 0.5/2 = 0.25 cm

Volume of the barrel of pen, V =π r2h

= (22/7)×0.252×7

= 1.375 cm3

Ink in the bottle, = one fifth of a litre

= (1/5)×1000 = 200 ml

Number of words written using full barrel of ink = 310

Number of words written by using this ink = (200/1.375)×310 = 45090.90 words

Round off to nearest hundred, we get 45100 words.

Hence the number of words written using the ink is 45100 words.

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