Due date: Oct. 26, 2017.

- Use the data in

http://www.utdallas.edu/~ammann/stat3355scripts/BirthwtSmoke.csv**[a]**Construct a 90% confidence interval for the proportion of mothers who smoke.**[b]**What sample size would be required to estimate this proportion to within 0.02 of the population proportion with 90% confidence if no prior bounds are used. What is this sample size if the sample proportion from part a is used as the prior bound?**[c]**Construct a 90% confidence interval for the mean birth weight of newborns with mothers who smoke. Do the same for mothers who don't smoke.**[d]**Use this data as a preliminary sample to determine the sample size required to estimate the mean birth weight for mothers who smoke to within 0.5 with 99% confidence. Do the same for mothers who don't smoke.**[e]**Construct a 90% confidence interval for the s.d. of birth weight for mothers who smoke. Do the same for mothers who don't smoke.

- Use the data in

http://www.utdallas.edu/~ammann/stat3355scripts/crabs.txt**[a]**There are 4 combinations of species and sex (B-M, B-F, O-M, O-F) for the crabs in this data. Construct separate 90% confidence intervals for mean BD in each of these groups.**[b]**Construct separate 90% confidence intervals for the s.d. of BD in each of these groups.**[c]**Construct a plot of BD versus FL using different colors for the two species and different plot symbols for Male and Female. Include a legend in the plot that shows which colors go with which species and which symbol goes with which sex.**[d]**Obtain separate correlation coefficients between BD and FL for each of the 4 combinations of species and sex. Compare these correlations to the overall correlation between BD and FL using all crabs. Interpret these correlation coefficients.

- Suppose that scores on the quantitative SAT exam among students in Texas public
universities who are taking Calculus I have approximately a normal distribution with mean 560 and
s.d. 95.
**[a]**What proportion of such students scored above 720?**[b]**What are the quartiles of these scores?**[c]**Suppose there are 45 students in a particular section of Calculus I at UTD and the mean QSAT score for these students is 620 with a s.d. of 85. Treat this class as a random sample of students at UTD who take this course and construct a 95% confidence interval for their mean QSAT. How does the mean at UTD compare to the mean for all such students in Texas?

2017-11-16