Suppose a class has 7 students. The average marks of these students in the mathematics examination is 62, and their variance is 20. A student fails in the examination if he/she gets less than 50 marks, then in worst case, the number of students can fail is _________.
Answer (integer)
0
Solution
<p>According to given data</p>
<p>${{\sum\limits_{i = 1}^7 {{{({x_i} - 62)}^2}} } \over 7} = 20$</p>
<p>$\Rightarrow \sum\limits_{i = 1}^7 {{{({x_i} - 62)}^2} = 140}$</p>
<p>So for any x<sub>i</sub>, ${({x_i} - 62)^2} \le 140$</p>
<p>$\Rightarrow {x_i} > 50\,\forall i = 1,2,3,\,\,.....\,\,7$</p>
<p>So no student is going to score less than 50.</p>
About this question
Subject: Mathematics · Chapter: Statistics · Topic: Measures of Central Tendency
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