Lengths of pregnancies (in humans) have a mean of 268.3 days and a standard deviation of 15.1 days. a woman tracked her pregnancy and found it to be 310 days. find the z score for 310 days. is such a length unusual? the z score is 2.8-2.76 2.76. (round to two decimal places as needed.) is a pregnancy length of 310 days unusual? a. yes, because its corresponding z score is less than 2. b. yes, because its corresponding z score is greater than 2. c. no, because its corresponding z score is greater than 2. d. no, because its corresponding z score is less than 2.