Arithmetic mean of following numbers is 1,2,2,3,3,3,4,4,4,4,5,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,7

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The arithmetic mean of the following numbers is $1,2,2,3,3,3,4,4,4,4,5,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,7$

A

$4$

B

$5$

C

$14$

D

$20$

Solution

Required mean

$=\frac{1 \times 1+2 \times 2+3 \times 3+4 \times 4+5 \times 5+6 \times 6+7 \times 7}{1+2+3+4+5+6+7}$

$=\frac{1+4+9+16+25+36+49}{28}$

$=\frac{140}{28}=5$

Standard 13

Quantitative Aptitude

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