In a class test, a student earns 3 marks for every correct answer and loses 2 marks for every incorrect answer. No marks are given for questions left unattempted. If Radhika scored 20 marks and had 12 correct answers, how many questions did she attempt incorrectly?
8
This is a marking-scheme problem: the total score equals the marks earned for correct answers minus the marks deducted for incorrect answers, while unattempted questions contribute nothing to the total.
Step 1 — Marks earned from the correct answers: \(12 \times 3 = 36\) marks.
Step 2 — Let the number of incorrect answers be \(w\). Each costs 2 marks, so the score is \(36 - 2w\).
Step 3 — Set this equal to the score obtained: \(36 - 2w = 20\), so \(2w = 16\) and \(w = 8\).
Check — \(36 - 2 \times 8 = 36 - 16 = 20\) marks, which matches. With 4 wrong answers the score would be 28, with 6 it would be 24, and with 10 it would be 16, so none of the other values fits.
8 option is correct.
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