You have not mentioned how long time you have worked in marketing & admin and in which type of industry u were employed, as it will also count in interview.
Secondly when interviewer asks you why should we hire you ,knowing you don't have experience in HR, there may be few but exact answers, such as:-
Dear Sir, after completing my Masters/ PG's i was regularly searching for HR jobs for me, i tried various places but unluckily i didn't proved in interview to them that i am suitable for their company,while my masters i gained so and so appreciations,awards,attended seminars etc( Must have such evidence if answering same),
As it was and is my dream to be a HR in a big organisation where i can give my best and even i can get good exposure too which enhances my knowledge as well as my C.V.'s strength,hence finally got an opportunity in above organisation and i joined there, to avoid gap in career, as a fresher very no organisation hired me as a HR, hence finally i joined, after joining i didn't loose my hope to work as a hr, and i kept searching for jobs and finally i am here for interview, though i don't have core experience in HR but as HR looks after major departments of any organsiation and has to deal with mostly all department in any organisations, i think my experience in marketing and Admin will sure help me out to perform my job as a HR, as any other candidate who is fresher or don't have experience of any department has to start from start to perform his/her job, even if company gives me chance to work then definitely my prior NON HR experience will support me up to perform my job.
Company will get a little much experienced employee rather than a HR fresher employee.
I seek a chance to prove my self .
As a professional you may concise ,edit or upgrade above answers and put it in proper way in front of interviewers to satisfy them.
Apart of above tricks they must find you suitable through your answers,body language,your hold on subject, your interest level in this job as well as in this company . Make sure and make them believe that you are pure HR material with experience and knowledge of Admin & Marketing.
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