\(power \ of \ a \ lens \ (D) = \frac{1}{focal \ length \ (m)}\) A lens has a power of -3.33 dioptres. Calculate the focal length and state what type of lens it is.

Developing a news-reading habit, she said, will be useful to anyone studying economics for IGCSE or IB, because they’ll have more examples to use when answering long, structured essay questions.