UPDATE 1-Administaff Q3 profit slumps 51 pct

* Q3 EPS $0.23 vs. $0.46 year ago

* Q3 rev falls 7 pct

Nov 2 (Reuters) - Administaff Inc ASF.N, a provider of human resources services, posted a 51 percent drop in quarterly profit as lower average number of worksite employees paid per month weighed on revenue.

The company posted a third-quarter profit of $5.8 million, or 23 cents a share, compared with $11.9 million, or 46 cents a share, a year earlier.

Revenue fell 7 percent to $390.9 million, partly due to an expected 10 percent drop in the average number of worksite employees paid per month, the company said. Revenue per worksite employee per month, however, rose 3 percent.

Analysts on average expected earnings of 22 cents a share, on revenue of $396.6 million, according to Thomson Reuters I/B/E/S.

Shares of the company closed at $24.82 Friday on the New York Stock Exchange. (Reporting by Amulya Nagaraj in Bangalore; Editing by Deepak Kannan)