Answer:
[895.05; 940.81]kWh
Step-by-step explanation:
Hello!
Be X: monthly electricity usage by a residential customer
X~N
σ²: 12100KWh²
To estimate the population mean using a 98% CI you have to use the following formula
[X[bar]± *
]
1-α: 0.98
α0.02
α/2: 0.01
1-α/2:0.99
n= 125
X[bar]= ∑X/n= 228565/125= 917.93
[917.93±2.326 * ]
[895.05; 940.81]
Using a 98% confidence level you'd expect that the interval [895.05; 940.81]kWh will include the average monthly electricity usage of residential customers.
I hope this helps!
Raw data:
Electric Usage
765
1139
714
687
1027
1109
749
799
911
631
975
717
1232
806
637
894
856
896
1272
1224
621
606
898
723
817
746
933
595
851
1027
770
685
750
1198
975
678
1050
886
826
1176
583
841
1188
692
733
791
584
1163
593
1234
603
1044
1233
1178
598
904
778
693
590
845
893
1028
975
788
1240
1253
854
1185
1164
741
1058
1053
795
1198
1240
1140
959
938
1008
1035
1085
1100
680
1006
977
1042
1252
943
1165
1014
912
791
612
935
864
953
667
1005
1063
1095
1086
810
1032
970
1099
1229
892
1074
579
754
1007
1116
583
763
1231
966
962
1132
738
1033
697
891
840
725
1031