In a classroom test, students were awarded +6 marks for each correct answer and -3 marks for each incorrect answer. No marks were given for unattempted questions. Radhika answered 10 questions correctly and scored a total of 42 marks. How many questions did she answer incorrectly?
Show answer & explanation
Correct answer: D
Explanation
Correct answers = 10
Marks obtained from correct answers = 10 × 6 = 60
Let incorrect answers = x
Total marks = 60 − 3x
60 − 3x = 42
3x = 18
x = 6