The formula to solve for Skewness (SK) = 3(mean-median)/standard deviation. If the mean is equal to the median with a standard deviation of 2.5, the graph is positively skewed negatively skewed symmetrical assymetric Cheryl has taken two quizzes in her history class. She scored 15 on the first quiz, for which the mean of all scores was 12 and the standard deviation was 2.4. Her score in the second quiz, for which the mean of all scores was 11 and the standard deviation was 2.0, was 14. In comparison to her classmates, did Cheryl do better on the first quiz or the second quiz and why? first quiz because the Z -value is 1.25 higher than the mean second quiz because the Z - value is 1.5 near the mean first quiz because the Z -value is 1.25 closer to the mean second quiz because the Z - value is 1.5 farther from the mean