Good Pisa results have become part of the brand of the Finnish school system, although in reality the research does not even measure what has been learned at school. So what is Pisa all about?
The membership fee for a DVD rental company is 10 zed and the rent for one DVD for a member is 2.50 zed, but for the others 3.20 zed. Last year, Tero spent zed 52.50 on the rental company, which included his membership fee. How much money would Tero have spent if he hadn’t been a member but still rented the same number of DVDs?