In a short quiz, 3 pupils scored 1 mark, 5 pupils scored 2 marks and 4 pupils scored 3 marks. How many pupils took the quiz?

Объяснение

Each pupil is counted once by the number attached to the score they earned, so the group contains 3 + 5 + 4 = 12 pupils. Adding the scores 1, 2 and 3 to get 6 counts the marks that could be earned instead, and no pupil is counted by that sum at all.