Example 4: In May 2006, Commonwealth Edison Company supplied electricity to residences for a monthly customer charge of $7.58 plus $0.08275 per kilowatt-hour (kWhr) for the first 400 kWhr
supplied in the month, and $0.06208 per kWhr for all usage over 400 kWhr in the month. (a) What is the
charge for using 300 kWhr in a month? (b) What is the charge for using 700 kWhr in a month? (c) If Cis
the monthly charge for x kWhr, develop a model relating the monthly charge and kilowatt-hours used.
That is, express C as a function of x.

1. why is a frequency distribution useful? it allows researchers to see the "shape" of the data. it tells researchers how often the mean occurs in a set of data. it can visually identify the mean. it ignores outliers. 2. the is defined by its mean and standard deviation alone. normal distribution frequency distribution median distribution marginal distribution 3. approximately % of the data in a given sample falls within three standard deviations of the mean if it is normally distributed. 95 68 34 99 4. a data set is said to be if the mean of the data is greater than the median of the data. normally distributed frequency distributed right-skewed left-skewed