Could you help

Q4. Twelve students are to take an exam in advanced oombinaton'cs. The exam room is set out in three rows of four desks. with the invigilator at the front of the room, as shown in the following diagram. INVIGILATOR Desk 1 Desk 2 Desk 3 Desk 4 Desk 5 Desk 6 Desk T Desk 3 Desk 9 Desk 10 Desk 11 Desk 12 (a) Find the number of ways the twelve students may be arranged in the exam hall. [1] Two oi the students. Helen and Nicky. are susoeoted of cheating in a previous exam. (b) Find the number of ways the students may be arranged if Helen and Nicky must sit so that one is directly behind the other (with no desk in between). For example Desk 5 and Desk 9. [2] (c) Find the number of ways the students may be ananged if Helen and Nicky must not sit next to each other in the same row. [3] lI