Data on residential energy consumption per capita (measured in million BTU) had a mean of 70.8 and a standard deviation of 7.3 for the states east of the Mississippi River. Assume that the distribution of residential energy use if approximately unimodal and symmetric.

a. Between which two values would you expect to find about 68% of the per capita energy consumption rates?

b. Between which two values would you expect to find about 95% of the per capita energy consumption rates? 

c. If an eastern state had a per capita residential energy consumption rate of 54 million BTU, would you consider this unusual? Explain. 

d. Indiana had a per capita residential energy consumption rate of 80.5 million BTU. Would you consider this unusually high? Explain.