8. use the data set e5.3 (birthweight-smoking) on baby’s birth weight and mother’s smoking status to answer the following questions (no need to answer the questions in the book). run a regression of birthweight on the binary variable smoker. a) what is the average value of birthweight for mothers who smoke? what is the average value of birthweight for mothers who do not smoke? b) is the effect of smoking on birth weight statistically significant? c) construct a 95% confidence interval for the effect of smoking on the birth weight.