What is the best approximation of the standard deviation of ${10,15,20,25,30}$ - $5,7.5$ or $10$ ?

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Answer 1 · 2016-09-23T15:04:15

Standard deviation can be best approximated by $7.5$ .

The mean of ${10,15,20,25,30}$ is

$(10+15+20+25+30)/5=100/5=20$ .

The deviations from mean are ${-10,-5,0,5,10}$ and

square of deviations are ${100,25.0,25,100}$ and

average deviation is ${100+25+0+25+100)/5=50$

and standard deviation is $sqrt50=7.071$

Hence, standard deviation can be best approximated by $7.5$ .

What is the best approximation of the standard deviation of {10,15,20,25,30}{10,15,20,25,30} - 5,7.55,7.5 or 1010?