A barrel of a fountain pen, cylindrical in shape, is 7 cm long and 5mm in diameter. A full barrel of ink in the pen will be used up when writing 310 words on the average, if a bottle of ink containing one-fifth of a litre then the number of words that can be formed is

Explanation

Volume of cylinder`=pir^2h`
Volume of a barrel`=22/7×0.25×0.25×7=1.375 cm^3`
Volume of ink in the bottle`= 1/5` litre`=1000/5=200 cm^3`
Therefore, total number of barrels that can be filled from the given volume of ink`= 200/1.375`
So, required number of words`=200/1.375×310=45090.9~~45091`.