Question

Q9. 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?​

Answer 1

Answer:

Let x be the number of copies that would occupy a self-length of 5.1m.

Number of copies 136 x

Length the self ( in m ) 3.4 5.1

Since, the number of copies and the length of the shelf are in direct variation.

∴

x=136= 5.1 3.4

⇒ 136×5.1=x×3.4

⇒ x= 3.4

136×5.1

⇒ x=204

∴ 204 copies will occupy a shelf of length 5.1m.

Answer 2

Let x be the number of copies that would occupy a self-length of 5.1m.

Number of copies 136 x

Length the self ( in m ) 3.4 5.1

Since, the number of copies and the length of the shelf are in direct variation.

$∴ \frac{136}{x} = \frac{3.4}{5.1}$

$⇒136×5.1=x \times 3.4$

$⇒x= \frac{136×5.1}{3.4}$

$⇒x=204$

∴ 204 copies will occupy a shelf of length 5.1m.