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## Class 9 math (India)

### Course: Class 9 math (India)>Unit 10

Lesson 1: Bar graphs

# Creating a bar graph

Sal creates a bar chart using data from a survey. Created by Sal Khan.

## Want to join the conversation?

• In a bar graph if you don't display all the data, is the problem still incorrect?
• From what I know, yes. The answer is incorrect if you don't have all the data on the graph
• can you do half numbers?
• You can do halves or any fractions. It just depends on your data.
If your numbers were: 1 1/2, 3, 4 1/2 and 5 1/2, then you'd want to do halves.
If your numbers were all whole numbers, there would be no reason to do halves.
• What is quantitative?
• When something is quantitative it means that it can be represented as a quantity, which is to say a number. In the case of statistics a variable is quantitative when it deals with numbers.
For example, a teacher's favorite class is chemistry, their favorite class is a categorical variable. But if you say the number of teachers whose favorite class is chemistry is 3, that would be a quantitative variable, because it deals with numbers.
• which side is the x- axis and which is the y- axis?
• The x-axis is the horizontal (side-to-side) line that goes from left to right. In this bar graph, the x-axis is labeled with courses: physics, chemistry, geometry, history, and language.

The y-axis if the vertical (up-and-down) line that goes from bottom to top. The y-axis is labeled with numbers to show the number of teachers.

Hope this helps!
• Is this the right practice to do for first year college statistics and probability? It seems a little too easy and I want to make sure I'm taking the correct course.
• The first few units cover the basics but by the end of the course it will get much more advanced. So you are in the right place!
• Can you use decimals in plot diagrams? Would the be wrong?
• Yes you can use decimals. On a plot diagram each line has a number. You would put 1 2 3 4. For decimals, on one line put 1, the 2nd line leave blank, the 3rd line would be 2. You would see 1 / 2 The / is the line with no number in-between 1 and 2 and that would be 1.5 Add more lines dependent on decimals.

So 2.3 would be 1 / / / / / / / / / 2 / / / / / / / / / / The 3rd / after 2 is 2.3 each / is .1

/ this is a line as the numbers, except you leave it blank. Even if it starts at 2.3 you do not put 2.3 under the line.
• Can continuous data be represented in bar graphs also or it is only represented through histograms?
• Shouldn't the Y axis say 20 teachers?
• Not really........ You just need enough room to fit all the data. No group had more than 10 so you didn't need to make room for 20. If you had a larger y-axis on the page all the information would look small and the entire top of the graph would be unused.
• What is a dependent variable and an independent variable?
• maybe you are asking "but why are they called dependent and independent?" when you study 2 variables, usually what you are interested in, is how they might affect each other in the real world. does change in one of them depend on a change in the other one?

example: does the amount of hair gel i use in my daily selfie cause a change in the number of likes i get? in this question, "number of likes" is the dependent variable (DV) and "amount of hair gel used" is the independent variable (IV).

But you say, telling me that doesn't make it any clearer! Ask, "when there is a change in one of the variables does it make sense that it could be due to a change in the other one?" Take the 2 variables and ask them in the form of questions: "Does a change in the amount of hair gel a person uses cause a change in the number of likes?" OR "Do the number of likes a person gets cause a change in the amount of hair gel that person uses?" The first question describes the true relationship. If a person gets more likes all of a sudden, it is due to some change that has already happened, in this case, more gel. Make sense?