Question IV (48 points, 6 points each)
 A problem of interest to health officials is to determine the effects of smoking during pregnancy on infanthealth. One measure of infant health is birth weight; a birth weight that is too low can put an infant at risk forcontracting various ilinesses. Our data sct contains data on births to women in the United States. Two variablesof interest are the dependent variable, infant birth weight in grams (bwght), and qan explanatory variable,average numbet of cigarettes the motber smoked per day during pregnancy (cigs). We also take other factorsinto accoun unt and specify the model as

where

The estimates of this equation, obtained using the method of ordinary least squares (OLS), are given in column(1) of Table 1. Standard errors are listed in parentheses.6. Interpret the coefficient on cigs. In particular, what is the effect on bught from smoking 10 more cigarettesper day?