1. A Xidian good student is a full time student whose average mark is above or equal to 90. TANG Cai Hong, ZENG Ju Di and CHEN Rui Qian has average mark of 91, 90, and 89 respectively. TANG Cai Hong and ZENG Ju Di are full time students while CHEN Rui Qian is part time. Write a PROLOG program to answer the questions of (1) Who are Xidian students, (2) Who is not a Xidian Good student, (3) Who has marks greater than or equal to 90. State any assumptions that you have made.