Take it from the Business 494 class St. Joseph's College, the Philadelphia 76ers' investment in Julius Erving enabled the club - "we're a private company and our figures are not available for public dissemination" - return a profit the past season.

Teacher Harry Rivkin, 39, an admitted pro basketball nut, assigned the marketing class project, "Was the 76ers' decision to purchase Erving in the New York Nets, in one of the time National Basketball Association deals, good business?"

The student team fanned out an talked with the 76er front office, the NBA office, Players Association, CBS television, player agents, bankers, tax men and sportswriters.The students also analyzed the corporate reports of the publicly owned NBA franchises in seattle, Milwaukee and New York (nicks).

The Sixers paid a reported $3.5 million to the Nets and gave Erving an estimated $2.5 million contract; the report said Erving also received a $125,000 annual expense account.

But the investigation developed that the-Sixers lost about $400,000 in 1975-76 and, scaling the house on the club's own estimate that they would draw 14,000 a game to the Spectrum without Erving and averaged 15,500 with Dr. J, those 1,500 extra customers per date turned a potential $198,000 loss for 1976-77 into a $31,000 profit.

THe students further found that since the team did make money, and (since no salaries are due to go up next reason), granted other expenses rise with inflation), there is only one reason for Philadelphia's recently announced ticket-price increase: to make more money . . .