Calcutta, March 13: An error in the mathematics paper of the ICSE class X board exams today left candidates confused.

Many students complained they couldn’t finish the paper because they used up a lot of their time puzzling over the “wrong sum” ? question 1(c) ? which carried four marks.

The compulsory question was: “A person invests Rs 10,000 for two years at a certain rate of interest compounded annually. At the end of one year this sum amounts to Rs 1,200. Calculate: (i) the rate of interest per annum; (ii) the amount at the end of the second year.” The “Rs 1,200” was, of course, absurd.

As soon as their students identified the mistake, the principals of some schools called up the council’s officials in Delhi and were told the examinees should read the second figure in the sum as “Rs 11,200”. But many other schools failed to contact the council and their students left the question unanswered.

Council deputy secretary Rita Wilson said “no student will be penalised” for the mistake whether or not their schools were able to rectify it.