Question

If the thickness of a pile of $12$ cardboard sheets is $45\mathrm{mm}$, then the thickness of a pile of $240$ sheets is _______ $\mathrm{cm}$.

Answer 1

Find the thickness of a sheets of pile.

It is given that, thickness of pile of $12$ cardboard sheets are $45\mathrm{mm}$.

Then, thickness of one cardboard sheet is, $\frac{45}{12}\mathrm{mm}$.

As we know that, the unitary method is the process of finding the value of something for one item (unit) an then using this value for calculating the value for several such items (units).

We will use the unitary method to find the thickness of pile of $240$ sheets.

$240$ cardboard will be $\frac{45}{12}\times 240=900\mathrm{mm}$.

So, thickness of a pile of $240$ sheets $=900\mathrm{mm}$.

As we know, both millimeters and centimeters is the unit to measure the length. One millimeter is equal to $0.1$ centimeters and $1\mathrm{cm}$ is equal to $10\mathrm{mm}$.

Therefore,

$900\mathrm{mm}=\frac{900}{10}$

$900\mathrm{mm}=90\mathrm{cm}$

Hence, If the thickness of a pile of $12$ cardboard sheets is $45\mathrm{mm}$, then the thickness of a pile of $240$ sheets is $90\mathrm{cm}$.