NCERT Exemplar Solutions
Class 7 - Mathematics - Unit 1: Number System - Problems and SolutionsQuestion 133
Class 7 - Mathematics - Unit 1: Number System - Problems and Solutions
Question. 133
133. A true–false test has 50 questions. Award +2 for every correct answer, −2 for every incorrect, and 0 for no answer. If Yash secured 94 marks, what are the possibilities of his correct/wrong/unattempted counts?
Answer:
Minimum correct = 47. Two possible distributions:
1) Correct 47, Unattempted 3.
2) Correct 48, Unattempted 1, Wrong 1.
Detailed Answer with Explanation:
Let \(r,w,n\) be right/wrong/blank with \(r+w+n=50\) and score \(2r−2w=94\Rightarrow r−w=47\).
Smallest \(r\) is 47 → \(w=0\), then \(n=3\). Or \(r=48\Rightarrow w=1\), then \(n=1\).