2990 people signed up for Ironman Wisconsin in 2015 Of the 2

2990 people signed up for Ironman Wisconsin in 2015. Of the 2990, 2338 actually finished. Data on the finishers is listed below: Finished under _____ hours: Frequency 9 1 9.5 3 10 22 10.5 50 11 101 11.5 117 12 204 12.5 202 13 272 13.5 211 14 199 14.5 205 15 211 15.5 146 16 157 16.5 130 17 107 a. Find the average finish time. b. Find the standard deviation of this distribution.
2990 people signed up for Ironman Wisconsin in 2015. Of the 2990, 2338 actually finished. Data on the finishers is listed below: Finished under _____ hours: Frequency 9 1 9.5 3 10 22 10.5 50 11 101 11.5 117 12 204 12.5 202 13 272 13.5 211 14 199 14.5 205 15 211 15.5 146 16 157 16.5 130 17 107 a. Find the average finish time. b. Find the standard deviation of this distribution.
2990 people signed up for Ironman Wisconsin in 2015. Of the 2990, 2338 actually finished. Data on the finishers is listed below: Finished under _____ hours: Frequency 9 1 9.5 3 10 22 10.5 50 11 101 11.5 117 12 204 12.5 202 13 272 13.5 211 14 199 14.5 205 15 211 15.5 146 16 157 16.5 130 17 107 a. Find the average finish time. b. Find the standard deviation of this distribution.

Solution

A)

Getting the mean, X,          
          
X = Sum(x) / n          
Sum(x) =    2559      
As n =    34      
Thus,          

X =    75.26470588   [ANSWER, AVERAGE FINISH TIME]  

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B)
          
Setting up tables,          
x   x - X   (x - X)^2  
9   -66.26470588   4391.011246  
1   -74.26470588   5515.24654  
9.5   -65.76470588   4324.99654  
3   -72.26470588   5222.187716  
10   -65.26470588   4259.481834  
22   -53.26470588   2837.128893  
10.5   -64.76470588   4194.467128  
50   -25.26470588   638.3053633  
11   -64.26470588   4129.952422  
101   25.73529412   662.3053633  
11.5   -63.76470588   4065.937716  
117   41.73529412   1741.834775  
12   -63.26470588   4002.42301  
204   128.7352941   16572.77595  
12.5   -62.76470588   3939.408304  
202   126.7352941   16061.83478  
13   -62.26470588   3876.893599  
272   196.7352941   38704.77595  
13.5   -61.76470588   3814.878893  
211   135.7352941   18424.07007  
14   -61.26470588   3753.364187  
199   123.7352941   15310.42301  
14.5   -60.76470588   3692.349481  
205   129.7352941   16831.24654  
15   -60.26470588   3631.834775  
211   135.7352941   18424.07007  
15.5   -59.76470588   3571.820069  
146   70.73529412   5003.481834  
16   -59.26470588   3512.305363  
157   81.73529412   6680.658304  
16.5   -58.76470588   3453.290657  
130   54.73529412   2995.952422  
17   -58.26470588   3394.775952  
107   31.73529412   1007.128893  
          
Thus, Sum(x - X)^2 =    238642.6176      
          
Thus, as           
          
s^2 = Sum(x - X)^2 / (n - 1)          
          
As n =    34      
          
s^2 =    7231.594474      
          
Thus,          
          
s =    85.03878218   [ANSWER, STANDARD DEVIATION]  

 2990 people signed up for Ironman Wisconsin in 2015. Of the 2990, 2338 actually finished. Data on the finishers is listed below: Finished under _____ hours: Fr
 2990 people signed up for Ironman Wisconsin in 2015. Of the 2990, 2338 actually finished. Data on the finishers is listed below: Finished under _____ hours: Fr

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