Note:
• In part (e) of each question below you MUST not say μ – rather you should say what μ represents (e.g., “true population mean body temperature of all men and women” in the first question).

## Body Temperatures

1. C=0.95
2. Confidence Interval
3. Z*=$$\pm$$-1.960.
4. 36.8$$\pm$$-1.960$$\frac{0.45}{\sqrt{130}}$$ = 36.73-36.89.
5. I am 95% confident that the true population mean body temperature of all men and women is between 36.73 and 36.89oC.

R Appendix.

( zstar <- distrib(0.025,type="q",lower.tail=FALSE) )

## Beetle Usage

1. C=0.95
2. Lower Confidence Bound
3. Z*=-1.645
4. 194.17-1.645$$\frac{15}{\sqrt{18}}$$ = 188.4
5. I am 95% confident that the true population mean thorax length of the Halticus oleracea beetle is greater than 188.4 mm (i.e., a lower bound).

R Appendix.

( zstar <- distrib(0.95,type="q",lower.tail=FALSE) )

## Internet Usage

Note:
• These questions are “sample size” and not “confidence region” calculations.
• Note that all sample size calculations should be rounded UP to a whole number. For example, in the second question below, note how 154.25 was rounded up to 155.
1. One should take a sample size of 219 household to achieve the desired level of confidence and margin-of-error.
2. One should take a sample size of 155 household to achieve the desired level of confidence and margin-of-error.
3. One should take a sample size of 876 household to achieve the desired level of confidence and margin-of-error.

R Appendix.

sigma <- 7.55
me <- 1
(zstar <- distrib(0.025,type="q",lower.tail=FALSE))
(round(zstar,3)*sigma/me)^2
(zstar <- distrib(0.05,type="q",lower.tail=FALSE))
(round(zstar,3)*sigma/me)^2
me <- 0.5
(zstar <- distrib(0.025,type="q",lower.tail=FALSE))
(round(zstar,3)*sigma/me)^2