# 6.12: Chapter 8 Solution (Practice + Homework)

Figure $$\PageIndex{23}$$

• The error bound and confidence interval will decrease.
• 136.

1. $$\overline x = 568,873$$
2. $$CL = 0.95$$ $$\alpha = 1 – 0.95 = 0.05$$ $$z_{\frac{\alpha}{2}}=1.96$$
$$E B M=z_{0.025} \frac{\sigma}{\sqrt{n}}=1.96 \frac{909200}{\sqrt{40}}=\ 281,764$$
3. $$\overline x − EBM = 568,873 − 281,764 = 287,109$$
$$\overline x + EBM = 568,873 + 281,764 = 850,637$$
4. We estimate with 95% confidence that the mean amount of contributions received from all individuals by House candidates is between $287,109 and$850,637.

139.

Higher

140.

It would increase to four times the prior value.

141.

No, It could have no affect if it were to change to $$1 – p$$, for example. If it gets closer to 0.5 the minimum sample size would increase.

142.

Yes

143.

1. No
2. No