Use the Empirical Rule to answer the following questions.

a$.$ The mean is

b$.$ The standard deviation is

c$.\%$ of the test scores are between $65$ and $75.$

d$.\%$ of the test scores are between $60$ and $80.$

e$.\%$ of the test scores are between $55$ and $85.$

f$.\%$ of the test scores are between $70$ and $75.$

g$.\%$ of the test scores are less than $70.$

h$.\%$ of the test scores are less than $75.$