A report by Montgomery County's cable television project manager says that Tribune-United Cable of Montgomery County finished first in an evaluation of service rates offered by the eight firms vying for the county's lucrative franchise.

The report, which has been presented to the county's Cable Television Advisory Committee, used a complicated mathematical formula to reduce all charges proposed by each firm to a raw score.

"The lower the resultant number, the higher the firm was ranked," said John Hansman, the county's cable television manager.

Following Tribune-United's raw score of 3.069 was Viacom Cablevision of Maryland Inc. (4.850), Warner Amex Cable Communications Co. (5.522), First County Cable (5.534), Montgomery Cable Communications Inc./Times Mirror Cable Television of Maryland (9.683), Montgomery Community Cablevision Inc. (13.1), Cablevision of Montgomery County (18.15) and Tele-Mont Communications (19.660).

When Carl Pilnick, the county's independent cable consultant, produced his first overall ranking of the eight firms, he looked at the same service rates and came up with a different set of findings. Tribune-United was first in Pilnick's service rate comparison, followed by Warner Amex, First County and MCCI/Times Mirror.

Hansman said that his approach stressed the importance of the length of each firm's "rate guarantee," the period during which prices would not be changed. He said Pilnick used a different approach.

Since it focuses on only one section of a rigorous evaluation process, the county's analysis will not result in any major reappraisals of the firms. But it is nonetheless important to consumers who hear of each mind-boggling piece of technology that will be offered and wonder how much it will cost.

Statistics indicate that about 70 percent of the existing cable systems in the country have only 12 channels. Alexandria and Arlington County both have a 36-channel capacity, but Montgomery may have as many as 47 satellite services alone, and perhaps as many as 124 separate channels to choose from, according to the firms' applications.

Most of the firms offer a wide array of so-called "premium service channels" like Home Box Office, Showtime, Cinemax and the Disney Channel, at costs ranging from $5.95 to $9.95 per channel. Many offer discounts if the subscriber picks two or more of these channels.

Most also offer a staggering array of services that range from banking and bill-paying to taking telephone messages and providing home security alarm set-ups. Art Barber, owner of the Montgomery Community firm, describes the system as giving the average household "a technological capability that would satisfy the Fortune 500."

Warner Amex's Tier I programming would have 52 channels, including 12 satellite channels, and would include all Washington-Baltimore stations. The Tier I cost would be $19.95 for installation and $3.95 per month. The company's Tier II programming would feature 82 channels, including 23 satellite channels. It would cost $29.95 for installation and $6.95 per month.

Warner's 14-channel QUBE home interactive service, which would allow subscribers to respond to polls and have pay-per-view television, could be installed with either the Tier I or II hook-ups for an installment charge of $29.95 and an additional $4.95 monthly.

Tribune-United's simplest offer involves a 43-channel service for $1.50 monthly (after an installation charge of $14.95) that includes all commercial and public stations within 30 miles of the county, a 24-hour sports channel, a Cable News Network channel, and with the additional availability of premium service channels like Cinemax, an all-movie channel.

Tribune-United's Tier II, at $5.95 per month, would offer 84 channels, several more "premium channels," as well as a package (at a cost of $50 per month) that would include the Dow Jones channel, a Reuters news service channel and three so-called "superstations" from Atlanta, Chicago and New York City. Tribune-United offers up to 119 channels for $8.95 per month (after the $14.95 installation fee), plus the added feature of home video games for an additional $12 a month.

In addition to its basic 33-channel system offering local access, community programs and a channel for the elderly ($49.95 for installment and no monthly fee), MCCI/Times Mirror offers a Tier II 65-channel system ($3.75 per month and $19.95 installment fee) that includes two superstations, CBS Cable, a health channel and an Associated Press news wire. Home interactive services are available on all systems, according to an MCCI/Times Mirror spokesman.

MCCI/TM offers up to 100 channels (for $7.75 per month), plus elaborate home interactive services that include home energy management and the ability to play video games when the contestants are at differing locations.

Tele-Mont offers the most satellite services with 47. Its premium service set-up offers up to 110 channels at an installation charge of $14.95 and monthly charge of $5.95. One Tele-Mont program option would allow the subscriber to select from 31 channels devoted to entertainment, family viewing, news and religion.

Viacom offers the greatest number of channels, with its most elaborate system including 124 channels, 12 satellite channels, three superstations and the Appalachian Community Service Network.

First County offers only slightly fewer channels (122) and home interactive services that include the ability to buy tickets and shop at home, and see Capital Centre programs.

Cablevision's optimal system offers 120 channels that would include a microwave link with New York to provide 11 out-of-town stations on two channels, three superstations and 11 satellite channels.

Montgomery Community's top-of-the-line service offers the fewest channels--71. The system also would have the ability to add computer-assisted instruction and make travel reservations. The basic monthly charge would be $12.95.