Study the following graph and answer the question.

In which year was the value per tonne the minimum?

2005

Lets find out one by one for each option .

1. 2005

Very per tonne of quantity = \(\frac{150 }{100}\) = 1.5

2. 2007

Very per tonne of quantity = \(\frac{330 }{150}\) = 2.2

3. 2009

Very per tonne of quantity = \(\frac{500 }{200}\) = 2.5

4. 2006

Very per tonne of quantity = \(\frac{150 }{75}\) = 2

So , value per tonne is  minimum in year 2005.