Sample: 1453
989= Without spills
99% Confidenece interval is given by:
[tex]ConfidenceInterval=Z_c*\sqrt[\placeholder{⬚}]{\frac{p(1-p)}{n}}[/tex]
For 99% confidence, the Z_c is:
[tex]Z_c=2.576[/tex]
And p is given by:
[tex]\begin{gathered} p=\frac{989}{1453}=0.68 \\ 1-p=0.319 \end{gathered}[/tex]
Substituing:
[tex]ConfidenceInterval=2.576*\sqrt[\placeholder{⬚}]{\frac{0.68*(0.319)}{1453}}=0.0315[/tex]
Finally, the way to find the intervals is given by:
[tex]p\pm ConfidenceInterval[/tex]
ANSWER:
Upper endpoint:
[tex]0.68+0.0315=0.7115\approx0.712[/tex]
Lower endpoint:
[tex]0.68-0.0315=0.6485\approx0.648[/tex]