The table to the right shows the results of a survey in whic

The table to the right shows the results of a survey in which 2590 adults from Country A, 1146 adults from Country B, and 1059 adults from Country C were asked if human activity contributes to global warming. Complete parts (a), (b), and (c). (a) Construct a 90% confidence interval for the proportion of adults from Country A who say human activity contributes to global warming. (Round to three decimal places as needed.)

Solution

Proportion of adults from country A who say actually contribute to global warming = 61/300 = 0.2033

p = 0.2033

1-p =0.7967

var = p(1-p)/n = 0.2033(.07967)/300 = 0.000540

std error = 0.0232

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z value for 90% = -1.68 and 1.68

Margin of error = 1.68(-.0232) =0.0390

Confidence interval = (0.2033-0.0390, 0.2033+0.0390)

= (0.1643, 0.2423)