91影视

$$\begin{gathered} x=171 \\ n=880 \end{gathered}$$

By dividing the complete number of wins by the sample size, the sample proportion is calculated:

$\hat{p}=\frac{x}{n}=\frac{171}{880}鈮�0.1943$

For confidence level$1-伪=0.95$, determine $z_{伪/2}=z_{0.025}$using table II (look up$0.025$in the table, the z-score is then the found $z-$score with opposite sign):

$z_{伪/2}=1.96$

Then, calculate the margin of error as follow:

$E=z_{伪/2}路\sqrt{\frac{\hat{p}(1-\hat{p})}{n}}=1.96脳\sqrt{\frac{0.1943(1-0.1943)}{880}}鈮�0.0261$

As a result, the confidence interval becomes:

localid="1650283792947" $0.1682=0.1943-0.0261=\hat{p}-E<p<\hat{p}+E=0.1943+0.0261=0.2204$

Need to find the likely direction for the bias.

Most people will not want to admit to driving through a red light and thus the proportion is likely higher, which means that we expect more than 171 respondents have actually driven through a red light.

These sources of bias are NOT sampling error and the margin of error includes ONLY sampling error, thus these sources of bias have not been included in the margin of error.