Part of the question that is mission: SAT math scores have a bell-shaped distribution with a mean of 515 and a standard deviation of 114.
Solution:
For scores between 401 and 629 = (515-114 = 401) and (515+114 = 619). In other words, the range given is within 1 standard deviation.
Based on Empirical rule, 1 standard deviation represents approximately 68% thus 68% is percentage of SAT scores between 401 and 629.
