Rule 4 states: "'A' is used before vowel 'U' when it is pronounced as 'you'. So, we have to use 'a' before university, but not 'an' before university."
Class 6 › English Grammar and Composition › Chapter 3: Articles: a, an, the › Topic: Rules for 'a' before consonants and 'an' before vowels
Aligned to the NCTB national curriculum.