2. [Module 9] In Norway, the distribution of birth weights for full-term infants whose gestational age is 40 weeks is approximately normal with mean 3500 grams and standard deviation 430 grams. An investigator plans to construct a study to determine whether birth weights of full-term babies whose mothers smoked throughout pregnancy have the same mean. If the true mean birth weight for the infants whose mothers smoked is as low as 3200 grams, or as high as 3800 grams, the investigator wans to risk only a 10% chance of failing to detect this difference. A two-sided test conducted at the 0.05 level of signicance will be used. What is the sample size needed for this study