Question

In: Statistics and Probability

2) The file ‘Energy’ contains the per capita energy consumption (in kilowatt-hours), for each of the...

2) The file ‘Energy’ contains the per capita energy consumption (in kilowatt-hours), for each of the 50 states and the District of Columbia during a recent year.

a) Compute the mean, variance, and standard deviation for the population.

b) What proportion of these states has per capita energy consumption within + or – 1 standard deviation of the mean, within + or – 2 standard deviations of the mean, and within + or – 3 standard deviations of the mean?

c) Compare your findings with what would be expected based on the empirical rule.

d) Repeat a) through c) with the District of Columbia removed. Have the results changed?

State Kilowatt Hours
Wyoming 24567
D.C 20073
Kentucky 19970
South Carolina 18865
Alabama 18399
Louisiana 17902
Idaho 17453
Tennessee 16993
Washington 16357
Indiana 16277
Mississippi 15885
Arkansas 15595
Texas 15059
North Carolina 15033
West Virginia 15022
Ohio 14593
Nevada 14511
Georgia 14465
North Dakota 14380
Oregon 14172
Delaware 13926
Oklahoma 13918
Montana 13743
Nebraska 13691
Virginia 13536
Iowa 13255
Kansas 12743
Missouri 12614
Florida 12393
Wisconsin 12103
Arizona 12067
Minnesota 12019
Maryland 11425
Illinois 10903
South Dakota 10806
Michigan 10491
New Mexico 10344
Utah 10273
Colorado 10002
Maine 9532
Vermont 9309
Connecticut 9081
New Jersey 8667
Alaska 8543
New Hampshire 8095
Pennsylvania 8006
Hawaii 7913
Massachusetts 7744
New York 7135
Rhode Island 6716
California 6396

Solutions

Expert Solution

a) Compute the mean, variance, and standard deviation for the population.

Mean 12999.22
Variance 14959701
Standard Deviation 3867.777

b) What proportion of these states has per capita energy consumption within + or – 1 standard deviation of the mean, within + or – 2 standard deviations of the mean, and within + or – 3 standard deviations of the mean?

   mean - 1s 9,092.95
   mean + 1s 16,905.48
64.7%
   mean - 2s 5,186.69
   mean + 2s 20,811.74
98.0%
   mean - 3s 1,280.43
   mean + 3s 24,718.01
100.0%

c) Compare your findings with what would be expected based on the empirical rule.

The values according to the empirical rule will follow the rule 68-95-99.7% and the values are close to the empirical rule.

d) Repeat a) through c) with the District of Columbia removed. Have the results changed?

Mean 12857.74
Variance 14238111
Standard Deviation 3773.342
   mean - 1s 9,046.09
   mean + 1s 16,669.39
68.0%
   mean - 2s 5,234.44
   mean + 2s 20,481.04
98.0%
   mean - 3s 1,422.79
   mean + 3s 24,292.69
98.0%

Yes, the results have changed.


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