BOSTON—A former senior executive at private equity firm TPG Capital was sentenced on Wednesday to three months in prison for participating in a vast U.S. college admissions fraud scheme by paying $50,000 to rig his son’s college entrance exam results. Prosecutors said Bill McGlashan, the former managing partner of TPG Growth and co-founder of The Rise Fund, paid to ensure that a corrupt test administrator would allow an associate to supervise his son’s ACT exam and secretly correct his answers. U.S. District Judge Nathaniel Gorton in Boston said McGlashan, 57, had tried to steal a spot at a prestigious university from a more deserving applicant, and that his sentence would show that “even the rich and famous cannot avoid the rule of law.” “You have let your enormous wealth, privilege and pride overwhelm all of what you want to stand for by your works of charity and philanthropy,” Gorton told …