48. Wireless access, again. The survey in Exercise 38 asking about wireless Internet access also classified the 798 respondents by income.

a) Do you expect the 95% confidence interval for the true proportion of all those making more than $75K who are wireless users to be wider or narrower than the 95% confidence interval for the true proportion among those who make between $50K and $75K? Explain briefly.

b) Find the 95% confidence interval for the true proportion of those making more than $75K who are wireless users.

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A D Wireless Other Internet Total 1 Users Users 2 Under $30K 34 128 162 3 $30K--$50K 31 133 164 4 $50K--$75K 44 72 116 5 Over $75K 83 111 194 Don't 6 know/refused 51 111 162 7 Total 243 555 798