Cholesterol levels among fourteen-year-old boys are roughly normally distributed, with mean 170 milligrams per deciliter (mg/dl) and standard deviation 30 mg/dl. You choose a simple random sample of 4 fourteen-year-old boys and find the average of their cholesterol levels. If you this many times, the mean of all the average cholesterol levels you get will be close to? If you this many times, the standard deviation of all the average cholesterol levels you get will be close to? In a simple random sample of 4 fourteen-year-old boys, the probability that the average cholesterol level is 200 mg/dl or less is close to?