Provide an appropriate response. the mean score of a placement exam for entrance into a math class is 80, with a standard deviation of 10. use the empirical rule to find the percentage of scores that lie between 60 and 80. (assume the data set has a bell- shaped distribution.)
a.95%
b.34%
c.47.5%
d.68%

The business cycle is the periodic but irregular up-and-down movement in economic activity, measured by fluctuations in real gross domestic product (gdp) and other macroeconomic variables. a business cycle is typically characterized by four phases—recession, recovery, growth, and decline—that repeat themselves over time. economists note, however, that complete business cycles vary in length. the duration of business cycles can be anywhere from about two to twelve years, with most cycles averaging six years in length. some business analysts use the business cycle model and terminology to study and explain fluctuations in business inventory and other individual elements of corporate operations. but the term "business cycle" is still primarily associated with larger (industry-wide, regional, national, or even international) business trends.

Answerless than average total cost, regardless of whether marginal cost is rising or falling;