Question

The barrel of a fountain pen,cylinderical in shape, is 7cm long and 0.5cm in diameter. A full barrel of ink in the pen can be used for writing 275 works on an average. How many words would be written using a bottle of ink containing one fourth of a litre?

Answer 1

first find the volume of cylinder
πr^2h,r=0.25cm
22/7*0.25*0.25*7
=1.375cm cube
we know that 1liter=1000cm cube
?=1.375cm cube
x=0.001375 liters
So if 275words is written by 0.001375 L
how many words will be written by 1/4 l=0.25l
275=0.001375
?=0.28
x=275*0.28/0.001375
x=56000
therefore 56000 words can be written by 1/4liters of ink

Answer 2

Pen: h=7cm , 2r= 5/10 = 1/2 => r=1/4 cm

Volume of barrel of pen = 22/7 x r2 x h

= 22/7 x 1/4 x 1/4 x 7

= 11/8 cm3

= ( 11/8 x 1/1000) litres [1cm3 = 1/1000 litres]

= 11/8000 litres

11/8000 litres => 275 words

1/4 litres => 'n' words

NOW, CROSS MULTIPLY

n x 11/8000 = 275 x 1/4

n = 275 x 1/4 x 8000/11

n = 50000

Therefore, 50000 words would be written using a bottle of ink containing 1/4 litres