JEE Mains · Maths · STD 11 - 13. statistics
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
- A \(5\)
- B \(3\)
- C \(4\)
- D \(0\)
Answer & Solution
Correct Answer
(D) \(0\)
Step-by-step Solution
Detailed explanation
\(20=\frac{\sum\limits_{ i =1}^{7}\left| x _{ i }-62\right|^{2}}{7}\) \(\Rightarrow\left| x _{1}-62\right|^{2}+\left| x _{2}-62\right|^{2}+\ldots .+\left| x _{7}-62\right|^{2}=140\) \(If\) \(x _{1}=49\) \(|49-62|^{2}=169\) then,…
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