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Population standard deviation known Two cities, Bradford and Kane are separated by a . Bradford claims that their mean family income is greater than Kane's Test Bradford's belief at the 5% significance level. Sample Mean Income Population Standard Deviation Sample Size Bradford $ 19,500 $2,500 40 Kane $18,600 $2,200 45 Population standard deviation known Two cities, Bradford and Kane are separated by a . Bradford claims that their mean family income is greater than Kane's Test Bradford's belief at the 5% significance level. Sample Mean Income Population Standard Deviation Sample Size Bradford $ 19,500 $2,500 40 Kane $18,600 $2,200 45