What are the mean and standard deviation of {34, 98, 20, -1200, -90}?

2 Answers
Apr 11, 2018

Mean = 227.6
Standard deviation = 489.9492

Explanation:

Calculate the mean as the sum of the numbers divided by the number of observations

Mean =(34 + 98 + 20 - 1200 - 90) / 5 = 227.6=34+98+201200905=227.6

Calculate the standard deviation as the square root of the sum of the squared difference each observation and the mean divided by the number of observations.

Standard deviation = sqrt( ( (34 - 227.6)^2 + (98 - 227.6)^2 + (20 - 227.6)^2 + ( - 1200 - 227.6)^2 +( - 90 - 227.6)^2 ) / 5 ) = 489.9492=(34227.6)2+(98227.6)2+(20227.6)2+(1200227.6)2+(90227.6)25=489.9492

Apr 11, 2018

Mean: -227.6 227.6, standard deviation is 489.9492 489.9492

Explanation:

Data: S= {34,98,20,-1200,-90}S={34,98,20,1200,90}

Mean : sum s/5= -227.6 s5=227.6

Variance square differences are (34-(-227.6))^2=68434.56(34(227.6))2=68434.56,

(98-(-227.6))^2=106015.36(98(227.6))2=106015.36, (20-(-227.6))^2=61305.76(20(227.6))2=61305.76,

(-1200-(-227.6))^2=945561.76(1200(227.6))2=945561.76, (-90-(-227.6))^2=18933.76(90(227.6))2=18933.76

Average variance square differences is

sigma^2=1200251.2/5=240050.24σ2=1200251.25=240050.24

Standard deviation is sqrt(sigma^2)=489.9492 σ2=489.9492