In an examination, a student scores 4 marks for every correct answer and loses 1 mark for every wrong answer. If she/he attempts all 60 questions and secures 130 marks, the number of questions she/he attempts wrongly, are?
Explanation
1. Equations Banana
Humein do jankariyan di gayi hain:
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Total Sawal: Student ne saare 60 sawal attempt kiye hain.
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Total Marks: Sahi jawab ke liye +4 aur galat ke liye −1 marks milte hain, aur total marks 130 hain.
4x−1y=130⟹4x−y=130—(Equation 2)
2. Step-by-Step Solution
Dono equations ko jodne par (Adding Equation 1 and 2):
Yahan +y aur −y cancel ho jayenge:
Ab x ki value nikalne ke liye:
Yani student ne 38 sawal sahi kiye hain.
Ab humein galat sawal (y) ki sankhya nikalni hai. Equation 1 ka istemal karte hain:
38 ko dusri taraf le jaane par:
