In a library 136 copies of a certain book require a shelf-length of 3.4 metre. How many copies of the same book would occupy a shelf-length of 5.1 metres?

Explanation

Let`x` be the number of copies that would occupy a self-length of `5.1`m.
Since, the number of copies and the length of the shelf are in direct variation.
∴`136/x=3.4/5.1`
`⇒ 136×5.1=x×3`
`⇒ x=(136×5.1)/3.4`
`⇒ x=204`
∴ `204` copies will occupy a shelf of length `5.1`m.