University professors have apologised to students after handing out exam papers with the answers stapled to the back.The geology exam at Manchester University descended into chaos when the error was spotted by a student.Invigilators dashed around the hall ripping out the answers from all papers - asking the 50 undergraduates to finish the exam.Some of the second-year students reacted with anger and stormed out before the end of the two-hour test, reports the Manchester Evening News.The results would have counted towards the final degree mark. But bosses have declared the exam void and students will be asked to carry out another test to complete the course.One student, who did not want to be named, said: "Some people didn't realise they had the answers and were angry that others had been given an unfair advantage. It was just a big mix-up."It's annoying that we have to do more work for this part of the course. The exams are over and the module is finished but we still have to do work on it."Prof Hugh Coe, head of earth, atmospheric and environmental sciences, emailed an apology to students following the exam, saying he was taking the error 'very seriously'.He wrote: "We realise how hard you are working to achieve the best results possible in your exams and recognise that events such as these only increase the stress of the examination period."Prof Colin Bailey, vice-president and dean of the Faculty of Engineering and Physical Sciences, said: "The university has apologised to the students involved and is currently carrying out an investigation to ensure that this error does not occur in the future."Source: orange news