<s>[INST] In a test, 5% of the candidates secured 80% + marks, 10% scored 70 – 79% marks, 15% scored 60 – 69% marks, 20% scored 50 – 59% marks and the remaining 50% scored below 50%. What percentage of candidates should be graded as ‘average’, assuming that the average mark is the mean of the highest and lowest marks in each category?[/INST]