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NDA 2013

Exam: NDA
Year: 2013
Subject: Mathematics
Chapter: Statistics

NDA 2013 · Mathematics · Statistics

Marks obtained by 7 students in a subject are 30,55 ,...

Marks obtained by 7 students in a subject are 30,55 ,

75,90,50,60,39

. The number of students securing marks less than the mean marks is

Options

A $7$
B $6$
C $5$
D $4$

Correct answer

D. $4$

Step-by-step solution

\begin{aligned} \bar{x} & =\frac{30+55+75+90+50+60+39}{7} \\ & =\frac{399}{7}=57\end{aligned}

number of students

=4

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