The arithmetic mean provides a single measure for a certain population, also called the average.
The sum of a set of numbers divided by the total number of numbers in the set is known as the arithmetic mean or arithmetic average in mathematics and statistics.
The ratio of the total number of observations divided by the sum of all the given observations is known as the arithmetic mean. For instance, if the data set contains 5 observations, it is possible to get the arithmetic mean by adding all 5 of the given observations and dividing by 5.
first you subtract 400 from 1722 to find the balance she will have which is 1322. then you must multiply 3.5 x 5= 17.50. now subtract 17.50 from 1322 and you get her balance after 5 months
