Q. For the following set of data, find the population standard deviation, to the nearest hundredth.139,126,51,61,77,109,112
List data set & mean: List the data set and find the mean (average) of the data.The data set is: 139,126,51,61,77,109,112.To find the mean, add all the numbers together and divide by the number of data points.Mean = (139+126+51+61+77+109+112)/7Mean = 675/7Mean ≈96.43
Subtract & square differences: Subtract the mean from each data point and square the result to find the squared differences.Squared differences:(139−96.43)2=42.572≈1812.20(126−96.43)2=29.572≈874.48(51−96.43)2=−45.432≈2063.88(61−96.43)2=−35.432≈1255.28(77−96.43)2=−19.432≈377.50(109−96.43)2=12.572≈158.04(112−96.43)2=15.572≈242.52
Add squared differences: Add all the squared differences together to find the sum of the squared differences.Sum of squared differences = 1812.20+874.48+2063.88+1255.28+377.50+158.04+242.52Sum of squared differences ≈6783.90
Find variance: Divide the sum of the squared differences by the number of data points to find the variance.Since this is a population standard deviation, we divide by the number of data points N=7.Variance =76783.90Variance ≈968.41
Calculate standard deviation: Take the square root of the variance to find the population standard deviation.Population standard deviation = 968.41Population standard deviation ≈31.11