Find the mean of the first six multiples of $4$: 

Data Handling

Data Interpretation

Data Interpretation is the process of making sense out of a collection of data that has been processed and presented in graphical representation. This collection may be present in various forms like Pie charts, line charts, bar graphs, tabular forms etc. and therefore, needs an interpretation of some kind. The questions can be based on sum, difference, average, ratio and percentage. Below are some types of charts and graphs:

1. Bar Graph: A bar graph is a chart representing data with rectangular bars. The heights and the lengths of these bar graphs are proportional to the values of data they represent. There are two types of the bar graph, one is called horizontal bar graph, and other is called vertical bar graph. Bar graphs made up of two axes, one is called x-axis, and other is called y-axis. In a horizontal bar graph, the y-axis shows the data categories and the x-axis shows the scale. In a vertical bar graph, the x-axis shows the data categories and the y-axis shows the scale.

2. Line Graph: Generally, a line graph is used to visualize values over a certain time period. It is basically used to change over time as various points of data connected by straight line on two axes.

3. Tabulation: In tables, data is described in the form of rows and columns. In DI table's questions, we are required to read data from table/tables, analyze the data and answer the questions asked on the basis of the given data.

4. Pie Charts: Pie charts are circular shaped graphs which are divided into sectors to represent numerical values. In a pie chart, the central angle of a particular sector is proportional to the quantity it represents. The larger the sector, the greater the value. The value of the central angle of the whole pie chart is ${360}^{\mathrm{o}}$.

Measures of Central Tendency

1. The median is the central value of an ordered distribution.

To find it,

(i) Order the data from the smallest to the largest.

(ii) For an odd number of data values in the distribution,

Median $=$ Middle data value

For an even number of data values in the distribution,

Median $=\frac{Sum of middle two values}{2}$

2. Mean $=\frac{Sum of all entries}{Number of entries}$

3. The range is the difference between the largest and the smallest values of a data distribution.

4. The mode of a data set is the value that occurs most frequently.

5. Standard deviation $\sigma =\sqrt{\frac{\Sigma {\left(x_i-\mu \right)}^2}{N}}$

$\sigma =$ Population standard deviation

$N=$ The size of the population

$x_i=$ Each value from the population

$\mu =$ The population mean

(i) Standard deviation is the square root of the variance.