Answer:
68% of pregnancies last between 250 and 282 days
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 266
Standard deviation = 16
What percentage of pregnancies last between 250 and 282 days?
250 = 266 - 16
250 is one standard deviation below the mean
282 = 266 + 16
282 is one standard deviation above the mean
By the Empirical Rule, 68% of pregnancies last between 250 and 282 days
