The table below shows the results of a survey in which 400 a

The table below shows the results of a survey in which 400 adults from the East, 400 adults from South, 400 adults from Midwest, and 400 adults from the West were asked if traffic congregation was a serious problem. See chart below

(a)Construct a 99 percent confidence interval for the proportion of adults midwest who say traffic congestion is a serious problem.

(b) Construct a 99% confidence interval for the population proportion of adults from the South \" \" \"

East 36%

South 33%

Midwest 25%

West 57%

Solution

a) for midwest n = 400

p = 25%

variance = 0.25(0.75)/ 400 = 0.1875

se = 0.4330

z value = 2.58