a. The percentage of arterial cord pH levels that are between 7.00 and 7.50 is (Round to two decimal places as needed.) %. Based on a recent study, the pH level of the arterial cord (one vessel in the umbilical cord) is normally distributed with mean 7.29 and standard deviation of 0.14. Find the percentage of preterm infants who have the following arterial cord pH levels. a. pH levels between 7.00 and 7.50. b. pH levels over 7.37.