A company produces steel rods. The lengths of the steel rods are normally distributed with a mean of 160-cm and a standard deviation of 1.2-cm. For shipment, 15 steel rods are bundled together. Find the probability that the average length of a randomly selected bundle of steel rods is less than 159.4-cm.
P(M < 159.4-cm) =

Enter your answer as a number accurate to 4 decimal places. Answers obtained using exact z-scores or z-scores rounded to 3 decimal places are accepted.