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…

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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

MARKS Content Team · Accepted Answer

Correct answer: 0. Applying the formula of variance we get, 20=(∑i=1)/(7xi-62^27) ⇒x1-62^2+x2-62^2+….+x7-62^2=140 If x_1=49 (taking the least possibility) 49-62^2=169 then, x2-62^2+….+x7-62^2=140-169=-29 Negative Number which is not possible, therefore, no student can fail.

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

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