The women’s 500m speed skating event is scored as an average of two attempts at the distance. The quickest total score wins. In Sochi the mean speed for the total speed across both races was 77.4 seconds, with a standard deviation of 1.3 seconds. What speeds represent the middle 50% of this distribution? Choose the z-score closest to the percentage you are looking for if the exact percentage is not available. 76.5 to 78.3 seconds. -.67 to .67 seconds. 76.1 to 78.7 seconds. 77.4 to 78.7 seconds.