Representation of two sets of data using bar-graphs is explained in this page.

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Consider the data: Number of glasses of water students drink during the school time. The data is collected for normal days and hot-sunny day. These two data sets differ. Can a bar graph be prepared for these?

- Yes, one bar graph can represent two sets of data
- Yes, one bar graph can represent two sets of data
- No, each data-set has to be having a separate bar-graph

The answer is "Yes, one bar graph can represent two sets of data".

Consider the number of glasses of water students drink during normal day and sunny day. The data is captured in the bar graph. Orange color bars represent data for normal day.

Green bars represent data for sunny day.

The data in this bar graph can also be read for details and compared.

Consider the number of glasses of water students drink during normal day and sunny day. The data is captured in the bar graph. Comparing normal day and sunny day, what is the increase in number of students who had `4` glasses of water?

- the increase is `7`
- the increase is `7`
- it did not increase, but decreased

The answer is "the increase is `7`".

**Multiple Data in a Bar-Graph** : Multiple sets of data can be plotted in a single bar graph. Such bar-graphs are also used to answer any comparative or quantitative questions.

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