## 10

Both sides of the equation are equal, so c = 10 is the solution when a = 20 and b = 2.

Practice Problem In the formula h = gd, find the value of d if g = 12.3 and h = 17.4.

### Use Statistics

The branch of mathematics that deals with collecting, analyzing, and presenting data is statistics. In statistics, there are three common ways to summarize data with a single numberâ€”the mean, the median, and the mode.

The mean of a set of data is the arithmetic average. It is found by adding the numbers in the data set and dividing by the number of items in the set.

The median is the middle number in a set of data when the data are arranged in numerical order. If there were an even number of data points, the median would be the mean of the two middle numbers.

The mode of a set of data is the number or item that appears most often.

Another number that often is used to describe a set of data is the range. The range is the difference between the largest number and the smallest number in a set of data.

A frequency table shows how many times each piece of data occurs, usually in a survey. Table 2 below shows the results of a student survey on favorite color.

 Table 2 Student Color Choice Color Tally Frequency red Iii!
0 0