Students in Prince William County, Va., have been on edge since learning that their Advanced Placement exams, which they took in May, went missing. (Bigstock photo)

Standing in the kitchen of a beach house in Sandbridge, ­17-year-old Serena Ralph pulled up the College Board website on her phone and braced for a moment of truth: the scores from her six Advanced Placement exams.

The tests represent the culmination of years of high school preparation and will lay the groundwork for her double-major at the University of Alabama, and when she went online July 7, her hard work — and her high school career — were already well behind her.

But what Ralph, a recent graduate of Patriot High in Nokesville, saw that day just added to her anxiety. Three of her exams had no scores. The reason: 362 AP answer sheets, on which students had painstakingly written essays and penciled in answers, had gone missing after her Prince William County high school submitted them.

The company that administers the College Board exams said Monday that it had located the exam sheets sometime over the weekend and would score them by the end of this week, delivering scores to students by the end of next week. Jason Baran, a spokesman for Educational Testing Service, said workers found the sheets in the company’s New Jersey warehouse late Friday “following our standard search procedure.”

“We apologize for any inconvenience this may have caused,” Baran said.

The students who took those exams went through days of anguish and confusion, preparing for the possibility of having to retake the exams, which usually require months of study and can run three hours or more.

The episode also raises questions about the security of the pencil-and-paper exams that must be shipped between physical locations. Baran said ETS is investigating how the exam sheets were misplaced but said this was the only instance of missing exam sheets this year.

“Is someone taking responsibility? Where was the integrity of the process compromised?” father Seth Goldrich wrote in an email to Prince William school officials after he learned that his daughter’s AP scores were missing.

Last year, Loudoun County Public Schools lost more than 250 SAT answer sheets after they were left in a high school mail room and never made their way to ETS. School workers located the boxes after about two weeks.

The missing AP exam sheets this month stirred anger and anxiety among students and their parents, who lamented that months of hard work — and the opportunity to earn college credit — could have been lost. High school students across the country take AP exams hoping to save thousands of dollars on college tuition and to increase their odds of graduating on time by knocking out general-education requirements before setting foot on the nation’s college campuses.

Before ETS found the answer sheets, students said the College Board offered them the opportunity to retake the exams. The school system also said teachers would be on hand to help refresh the study materials. But that was little consolation to recent graduate Brett Goerl, who recoiled at the idea of foregoing a hard-earned Florida vacation to study. Even with a crash course, Goerl said he was not confident he would do as well after being out of the classroom for two months.

“Making students retake an AP exam in August after they’ve been on vacation is really just setting them up for failure,” said Goerl, who is bound for the University of Virginia and is still awaiting his AP scores for calculus and Spanish.

Goerl said he was furious at the prospect of having to relearn material in college that he mastered in AP courses.

“If I studied hard enough and spent a morning in May completing an exam, the College Board promised me that I could receive college credit for my efforts,” Goerl said.

Ralph, the recent Patriot High graduate, said she was banking on the exams to provide her with enough college credit to allow her to complete two majors — computer science and economics — in four years. An aspiring mobile app developer, she said she hopes an economics degree will help prepare her for starting her own company.

But when she learned her tests were missing, she considered dropping the economics major from her plans. Upon hearing that ETS had found the exam sheets, she said she would not breathe easy until she sees her scores.

“I’m very relieved, but I’m still a little anxious until I have the actual scores,” she said.