Pregnancy length (in days) is a normally distributed random variable with a mean of 266 days and a standard deviation of 16 days. births that occur before 245 days are considered premature. what is the probability that a randomly selected newborn baby is premature?

The 245 day cutoff has z score (245 - 266) / 16 = -1.3125. The probability that the baby was born prematurely is the probability of having the pregnancy length less than 245 days, or having a z-score less than -1.3125. The probability of having a z-score less than -1.3125 can be looked up on a z-score table: 0.0951