Chapter 2 problems (pp.33-36):  2.2, 2.8, 2.9, 2.19 2.28
2.2:
Compute standard deviation and range for duration of hospitalization
Days in order: 3,3,3,4,4,5,5,5,5,6,7,7,8,8,9,9,9,10,11,11,11,11,14,17,30
Range is biggest number minus smaller number
Range 30-3= 27
Range= 27
Calculate standard deviation by hand
Compute the mean of the 
http://www.ehow.com/how_2107320_calculate-standard-deviation.htmldata set.
Mean = 215/25= 8.6
Calculate the deviance of each piece of data from the mean of the data set. This is done by subtracting the total mean from each individual number.
3-8.6=-5.6 , 4-8.6= -4.6, 5-8.6= -3.6, 6-8.6= -2.6, 7- 8.6= -1.6, 8-8.6= -0.6, 9-8.6= 0.4, 10-8.6= 1.4, 11-8.6= 2.4, 14-8.6=5.4, 17-8.6=8.4, 3-8.6= 21.4
Square each of the individual deviations then add them
31.36×3 + 21.16×2 + 12.96×4 + 6.76 + 2.56×2 +0.36×2 + 0.16×3 + 1.96 +5.76×4 +29.16 +70.56 + 457.96 = 784.08
Divide the number you got from adding the squared differences together by one less than the data set.
25 sets – 1 = 24 so 784.04/ 24= 32.72
Calculate the square root of the result of the previous step. The result of this calculation is the standard deviation. 32.72 = 5.72013986
Standard deviation= 5.72013986
2.8
Diopters
0.2-0.3 0.15+ 0.35/2= 0.25
0.4-0.5 0.35+0.55/2=0.45
0.6-1.0 0.55+1.05/2= 0.8
1.1-2.0 1.05+2.05/2= 1.55
2.1-3.0 2.05+3.05/2=2.55
3.1-4.0 3.05+4.05/2=3.55
4.1-5.0 4.05+ 5.05/2=4.55
5.1-6.0 5.05+6.05/2=5.55
0.25+0.45+0.8+1.55+2.55+3.55+4.55+5.55= 19.25
Mean=19.25/8= 2.40625
2.9
0.25-2.40625= -2.15625 squared= 4.64941
0.45-2.40625= -1.95625squared = 3.82691
0.8-2.40625= -1.60625squared = 2.58004
1.55-2.40625= -0.85625squared = 0.73316 sum= 27.59716
2.55-2.40625= 0.14375squared = 0.02066 27.59716/7=3.94245
3.55-2.40625= 1.14375squared = 1.308163.94245= 1.98556037
4.55-2.40625= 2.14375squared = 4.59566
5.55-2.40625= 3.14375squared = 9.88316
Standard…