Western Cape pupils who wrote the Independent Examination Board's (IEB) final physical science exam last week would not "carry the can", the board said, after an error in the paper made it impossible for pupils to answer a question.

Information was left off a graph, which was required for pupils to calculate velocity, among other forces.

In the Western Cape, pupils at 11 schools wrote the exam, including Reddam, Somerset College outside Somerset West, Cedar House in Kenilworth, Bridge House in Franschhoek and Elkanah House in Blaauwberg.

IEB chief executive Anne Oberholzer explained today: "We print, proof read and sign off the exam, and then it goes to print. But if it is printed on a different machine, information can become affected - especially graphs and diagrams."

Around 4 240 pupils at 170 schools wrote the exam nationally.

"Pupils won't be disadvantaged, because it's not their problem," she said. "There are systems and procedures in place to deal with these difficulties, and they won't carry the can."

She said there were "a number of ways" to calculate how pupils may have been affected - for example, how much time they had dedicated to trying to answer the question.

"We receive detailed school-based assessments. For example, if a pupil normally comes third in their class, but now comes 20th, then we know they have been particularly affected," she explained.

It would also be researched how many pupils did not finish the exam or left out other questions in order to calculate the impact.