Use the columns monthly_spend_k, transactions, avg_balance_k and online_pct, scaled with StandardScaler (call the result X). Fit KMeans(n_clusters=4, n_init=10, random_state=0) on X.
The centres are in scaled units. Turn them back with scaler.inverse_transform and store the monthly_spend_k of the highest-spending centre, rounded to 1 decimal, in result.
import io
import pandas as pd
cards = pd.read_csv(io.StringIO("""customer_id,monthly_spend_k,transactions,avg_balance_k,online_pct
701,42.9,59,173,69
702,26.6,29,12,54
703,50.7,56,166,78
704,19.1,19,17,41
705,6.7,10,38,8
706,15.3,34,9,53
707,108.3,28,487,29
708,53.8,51,178,74
709,18.9,39,12,45
710,87.9,36,353,44
711,46,65,120,72
712,77.4,32,483,43
713,32.3,52,179,75
714,18.2,33,13,41
715,90.5,28,387,26
716,55.1,55,151,57
717,24.7,37,11,70
718,10.6,18,34,23
719,101.9,16,453,25
720,29.2,49,180,71
721,17.9,33,9,42
722,7.8,11,34,22
723,33.5,64,154,84
724,9.8,15,27,37
725,16.9,25,26,44
726,97.9,20,319,42
727,6.8,13,51,14
728,20.3,27,13,42
729,10.3,16,34,16
730,32.8,53,126,81
731,8.1,11,33,29
732,27.3,23,12,42
733,45.1,52,81,70
734,19.1,35,12,64
735,52,55,148,76
736,54.9,52,135,78
737,7.2,12,53,17
738,10.3,12,53,23
739,15.2,28,19,44
740,47.9,63,128,75
741,84,18,354,25
742,7.5,10,45,26
743,8.7,13,62,38
744,75.6,26,413,53
745,19.5,28,19,48
746,43,44,134,81
747,18,39,14,48
748,12,4,52,15
749,16.6,27,15,56
750,5.4,13,52,26
751,81.9,23,427,29
752,9.1,12,56,15
753,20.8,28,21,45
754,49.3,55,150,73
755,103.5,21,409,24
756,8.9,11,31,15
757,16.9,33,17,38
758,17.5,28,29,26
759,14.1,25,20,35
760,83.1,34,342,47
761,19.7,37,11,31
762,24.1,38,12,41
763,21.2,41,21,39
764,22.6,31,17,45
765,46.5,55,117,67
766,56.2,55,180,84
767,7.7,9,40,30
768,9.1,15,45,5
769,43.7,53,186,67
770,22,37,15,52
771,8.1,10,41,24
772,10,8,38,20
773,17.8,30,9,45
774,6,8,38,9
775,46.8,56,159,68
776,22.5,31,11,43
777,90.3,23,429,37
778,8.4,17,20,33
779,26.9,31,13,39
780,40.6,50,185,71
781,33.2,46,125,84
782,49.9,47,132,73
783,13.5,26,20,49
784,60.9,33,135,86
785,45.3,45,184,79
786,105.3,19,466,33
787,7.7,12,32,36
788,21.1,32,20,32
789,14.2,26,0,20
790,55.4,31,451,23
791,17.2,29,5,39
792,22.3,20,15,56
793,26.8,28,4,40
794,95.5,32,378,51
795,93.6,27,485,20
796,109.6,12,432,45
797,45.3,43,156,77
798,7.8,9,39,20
799,43.2,51,114,87
800,7.3,11,29,15
801,20.8,28,16,37
802,49,47,159,86
803,25.8,31,20,49
804,10.3,14,44,14
805,45.8,52,161,79
806,20.2,32,14,23
807,50.4,48,195,68
808,20.3,22,13,44
809,93.1,29,372,11
810,47.9,52,200,67
811,86.3,23,416,52
812,43.4,54,135,78
813,9.7,10,53,26
814,39.3,58,210,86
815,10.3,14,54,15
816,89.8,26,351,31
817,5.4,20,32,20
818,14.1,34,13,50
819,10.9,12,38,36
820,86.1,19,372,36
821,100.4,26,453,37
822,38.6,57,118,68
823,8.8,15,45,23
824,9,10,37,28
825,18.6,26,16,40
826,39.2,52,127,92
827,67.6,21,462,28
828,7.6,7,54,18
829,81.9,25,440,33
830,23.3,19,21,23
831,21.4,23,13,47
832,20.2,32,20,56
833,86.7,32,509,15
834,7.2,8,48,22
835,12.4,11,30,36
836,16.4,39,19,69
837,54.3,59,152,68
838,39.8,40,174,85
839,10.1,11,37,12
840,4,11,54,23
841,86.4,22,418,32
842,10.2,16,21,19
843,5.9,7,46,36
844,20.5,31,22,38
845,49.1,50,177,76
846,88.4,29,476,10
847,17.3,25,12,53
848,5.9,7,44,16
849,79.6,28,437,16
850,7.3,14,37,18
851,37.5,63,131,81
852,23.4,36,22,52
853,97.4,20,454,38
854,6.8,9,50,7
855,27.7,34,19,51
856,7.2,10,62,26
857,77.3,29,465,22
858,4.2,8,49,15
859,45.1,49,161,69
860,90.2,27,389,13
861,90.3,21,339,21
862,47.7,57,169,77
863,82.4,29,372,36
864,7.6,13,33,14
865,92.5,23,436,30
866,8.8,10,45,14
867,78.6,18,411,35
868,76.3,31,395,35
869,10.7,18,60,28
870,5,13,26,8
871,14.3,36,17,49
872,35.5,57,152,71
873,17.1,28,14,46
874,12.1,13,30,31
875,47.2,50,127,75
876,8.4,13,41,28
877,82,25,381,39
878,18.9,27,20,43
879,44.1,52,180,67
880,15.3,29,12,47
881,47.7,49,145,60
882,81.8,30,290,36
883,12.7,29,2,50
884,22.2,31,19,64
885,8.6,22,41,28
886,17,30,13,47
887,50.4,80,143,63
888,18,31,7,47
889,95.9,25,451,14
890,111.8,19,319,23"""))Store your final answer in a variable named result.
Each hint gives a little more help. Try on your own first.
Run your code to see the output here.