For each problem, select the best response.

(a) Scores on the mathematics part of the SAT exam in a recent year were roughly Normal with mean 568 and standard deviation 120. You choose an SRS of 100 students and average their SAT math scores. If you do this many times, with a sample of size 100 each time, the mean of the average scores will get close to

A. 56.8
B. 5.68
C. 568
D. None of the above.

(b) A newborn baby has extremely low birth weight (ELBW) if it weighs less than 1000 grams. A study of the health of such children in later years examined a random sample of 219 children. Their mean weight at birth was $\bar {x} =$ 810 grams. This sample mean is an unbiased estimator of the mean weight $\mu$ in the population of all ELBW babies. This means that

A. the sample mean $\bar {x}$ will have a distribution that is close to Normal.
B. the average sample mean $\bar {x}$, over all possible samples, is equal to $\mu$.
C. the sample mean $\bar {x}$ is always equal to $\mu$.
D. None of the above.

(c) Scores on the mathematics part of the SAT exam in a recent year were roughly Normal with mean 568 and standard deviation 120. You choose an SRS of 100 students and average their SAT math scores. If you do this many times, with a sample of size 100 each time, the standard deviation of the average scores will get close to

A. 1.2
B. 120
C. 12
D. None of the above.