A federal judge in Illinois has dismissed a lawsuit accusing the College Board and 40 highly selective private colleges and universities of conspiring in a price-fixing scheme to inflate tuition costs.

In a decision released last week, U.S. District Judge Sara Ellis determined that the plaintiffs, a Boston University student and an alum of Cornell University, “have not plausibly alleged that Defendants entered into an agreement” demonstrating collusion on pricing.

The class action lawsuit, filed just shy of a year ago, alleged that the defendants overcharged tuition for students of divorced or separated parents by considering the financial information of the noncustodial parent, as well as the custodial one, in calculating financial aid awards. The plaintiffs claimed that the formula increased their tuition by an average of $6,200.

The lawsuit alleged that the price-fixing arrangement among the 40 institutions began in 2006, when the College Board began requiring both parents to submit financial information for its College Scholarship Service profiles, regardless of the student’’ custody arrangements. While last week’s decision acknowledged the practice inflated tuition prices at the institutions named, Ellis found no evidence that they had conspired.

“Nothing in Plaintiffs’ complaint suggests that the University Defendants exchanged their own internal financial aid decisionmaking processes or guidelines or otherwise shared with the other University Defendants the amount of financial aid they planned to offer a particular student,” she wrote. “Nor does the complaint allege that the University Defendants all agreed on the same exact formula for calculating financial aid based on the [noncustodial parent’s] financial information.”