3.166 Gestation Periods of Humans. Gestation periods of humans have a mean of 266 days and a standard deviation of 16 days. Let y denote the variable "gestation period" for humans. a. Find the standardized variable corresponding to y. b. What are the mean and standard deviation of the standardized variable? c. Obtain the z-scores for gestation periods of 227 days and 315 days. Round your answers to two decimal places. d. Interpret your answers in part (c). e. Construct a graph similar to Fig. 3.15 on page 134 that shows your results from parts (b) and (c)