Using the 68-95-99.7 Rule

Question

The length of human pregnancies from conception to birth varies according to a distribution that is approximately normal with a mean of 266 days and a standard deviation of 16 days. Using the 68-95-99.7 Rule, between what two days will approximately 68% of the pregnancies be centered about the mean?

Answer 1

266 + or + 16 = 282 to 250 days

68% of the time pregnancies will be between 282 and 250 days

that's the mean + or - one standard deviation