Key West businessman David A. Cox, a contestant 9 p.m. Friday on ABC-TV’s Shark Tank, describes himself as “an old soul.”

“I have always been attracted to people who are older than myself,” he says. “My partner is 64, I’m 29.”

In 2011, Cox married Allen Gallant in Massachusetts. They divide time between South Florida and Provincetown, Mass.

Cox’s fondness for older men led him in a roundabout way to the TV reality show, which features aspiring entrepreneurs and celebrity business execs.

Two years ago, he ran an Apple dealership in Cape Cod, Mass.

“I was asked to teach this classes open to the public in basic Mac,” said Cox, a computer geek. “Word spread that I was good at it. . . . . We had people sitting on the floor, leaning on the window sill. One day while teaching I had this realization that every person there was over 50.”

Soon he began giving one-on-one training sessions and named his blossoming business The Mac Guru.

His customers gave him the idea. “I’d be at someone’s house and they’d say, ‘I can’t talk, the Mac guru is here.’ ’’

Cox also launched a website, PC Classes Online, featuring basic computer courses including “New to Mac” and “Intro to Windows 7.”

From home, Cox launched a computer podcast called Tech Talk America. A fan suggested he go on Shark Tank, but Cox had reservations.

“I was worried because I saw them be mean to people. I saw people cry,” he says.

Still, he emailed an application to Shark Tank, pitching his business as a unique boon for older computer users who want to develop their skills.

He got a quick response from a Shark Tank scout. “The first sign that something might result from this — the person who called me back said this would be perfect for my mother.”

Chosen from more than 30,000 potential contestants, Cox agreed to be on the show and asked if he could appear with his friend, Emmy-winning writer-comedian Bruce Vilanch, whom he met nine years ago at a film screening.

Shark Tank producers loved the idea and so did the former Hollywood Squares star.

“He called and said he had an opportunity to be on Shark Tank and that he thought he would have a better opportunity if he had a celebrity with him,” Vilanch, 63, recalls. “I like him, and he’s a friend. He came up with a good idea. And he taught my mother how to Skype.”

All was well until Shark Tank informed Cox he would need to be in Los Angeles to tape the show on July 11— Bear Week Provincetown, when hairy men of all sizes invade the gay resort town.

“It was horrible,” Cox says. “Why? It’s the one week I look forward to all year.”

STEVE ROTHAUS