4. In a large city, the percent of total spending that households devote to housing is normally distributed, with mean u and standard deviation o= 9%. I select a simple random sample of four young households and determine the percent of their total spending that is devoted to housing. The four percentages are
 33%  39%  32%  36%
Based on these data, a 99% confidence interval forμis
(A)35%±5.78%.
(B)35%±8.82%
(C)35%±11.59%
(D)35%±23.18% 

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統計： A(2), B(1), C(3), D(0), E(0) #2766592