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

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

Apr 11, 2018

Mean: -227.6 , standard deviation is 489.9492

Explanation:

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

Mean : sum s/5= -227.6

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

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

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

Average variance square differences is

sigma^2=1200251.2/5=240050.24

Standard deviation is sqrt(sigma^2)=489.9492