To investigate the satisfaction level with garbage removal in an urban area,a telephone survey was taken of 100 residents.Seven residents reported being satisfied with their garbage removal.A 90% confidence interval for the true percentage of all satisfied residents would be _____.
A)[0.0000,0.2034]
B)[0.0371,0.1029]
C)[0.0039,0.1361]
D)[0.0280,0.1120]
E)[0.0078,0.1400]

Question

Quizplus · Accepted Answer

The confidence interval is calculated using the formula for a proportion: p̂ ± Z*(√(p̂(1-p̂)/n)), where p̂ = 7/100 = 0.07, Z for 90% confidence is 1.645, and n = 100. This results in the interval [0.0280, 0.1120].

To Investigate the Satisfaction Level with Garbage Removal in an Urban