Question

A book which has 400 pages is found to have a thickness of 20cm.what is thickness of each sheet in mm?

Answer 1

The thickness of each sheet is 0.5mm

Explanation:

`1cm = 10mm`
So `20cm = 200mm`

Since there are 400 pages in your book and they have a thickness of 200mm, then you can think of it this way

`400 "pages" = 200mm`
`1"page" = x mm`

`x "mm"=(1times200)/400`

`x"mm"=1/2`

`x=1/2` mm

Answer 2

Each page is `0.5mm` thick.

Explanation:

Many students get questions like this wrong because they don't feel comfortable dividing a small number by a bigger one.

However, the pages in a book are very thin, so we are expecting a value less than `1mm` for the thickness of each page.

The units are a clue about which vakue to divide by which.

The thickness will be `mm` per page, so divide the thickness by the number of pages:

`20 cm = 200 mm`

`(200 mm)/(400 " pages" ) = 0.5 mm` / page