Question

the barrel of a fountain pen cylindrical in shape with with radius of base is 0.7 cm and 5 cm long want search barrel in the pain can be used to write 300 words A Barrel full of field has a capacity of 14 cubic centimetre can be used to write how many words are approximately​

Answer 1

The fountain pen is of cylindrical type.

Height of cylindrical fountain pen = 5cm

Radius of base = 0.7 cm

Volume, V of a cylinder is as follows:

$V = \pi r^2 h$

where $r$ is the radius of base of cylinder

$h$ is the height of cylinder

Putting the values of r and h and using $\pi = \frac{22}{7}$

$V = \dfrac{22}{7} \times 0.7^2 \times 5\\\Rightarrow \dfrac{22}{7} \times \dfrac{7\times 7}{10 \times 10} \times 5\\\Rightarrow \dfrac{77}{10}\\\Rightarrow 7.7 cm^3$

It is given that it writes 300 words.

Using unitary method:

$7.7 cm^3$ can write = 300 words

$1 cm^3$ can write = $\frac{300}{7.7}$

$14 cm^3$ can write = $\frac{3000}{77} \times 14$

$\Rightarrow \dfrac{6000}{11}\\\Rightarrow \tilde \ 545\ words$

$14 cm^3$ can write approx 545 words.