Graphs - Histograms
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LearningTranscript
00:00Hi kids! Today we will learn about a type of data chart, which is called histogram.
00:08So let's start!
00:10What are data charts and why we use them?
00:14Data chart is a type of diagram or graph where data is represented by various symbols,
00:22such as bars in bar graph, lines in line graph, or slices in pie chart.
00:31Charts makes it easy to understand large quantities of data and the relationship between parts of data.
00:40Data given in the form of charts is read more quickly.
00:46There are different types of data charts.
00:50So let's now learn a type of data chart, which is called histograms.
00:56Histogram is also a bar chart, with rectangular bars like a bar chart.
01:03Here too, lengths of bars represent the values of entities.
01:10Difference from bar chart is that,
01:13in bar chart, the width of bar chart does not represent any value, but the name of entity.
01:22But in histograms, the width of rectangular bars represent class interval.
01:29That is, entire range of values are divided into series of small intervals,
01:36and then we count how many values fall into each interval.
01:42Let's learn more on it using some examples.
01:46Weight of some people was noted down.
01:49Weights were in the range from 100 to 250.
01:55So, small class intervals or categories can be made like this.
02:02Also, each category or class interval is same size.
02:08Like here, each class interval is 25 in size.
02:32And then calculated how many people have weight in each class interval.
02:50Like here, it's calculated.
02:525 people have weights in the range of 100 to 125 pounds.
03:0115 people have weights in the range of 126 to 150 pounds, and so on.
03:12Now let's see how we write down this data in the form of a histogram.
03:18First of all, the title of the graph will be Weight of People in Pounds.
03:25One form of data we have is number of people.
03:29It's a numeric data and can be easily accommodated on a simple scale along any axes.
03:38Let's make the scale of y-axis.
03:43We have number of people in the range of 1 to 40 in every class.
03:50So we will make scale according to that.
03:54Second information we have is weights of people in pounds, which is already divided into class intervals.
04:03Now, on x-axis too, make a scale showing class intervals.
04:11According to data, 5 people have weights in the range of 100 to 125 pounds.
04:22So make a bar up to the mark of 5.
04:27Next we have 15 people in the range of 126 to 150 pounds.
04:36So make a bar up to the mark of 15.
04:40Next we have 23 people in the range of 151 to 175 pounds.
04:49So make a bar up to the range of 23.
04:53Next we have 37 people in the range of 176 to 200 pounds.
05:03So make a bar up to the range of 37.
05:07Next we have 15 people in the range of 201 to 225 pounds.
05:16So make a bar up to the mark of 15.
05:20Next we have 4 people in the range of 226 to 250 pounds.
05:28So make a bar up to the mark of 4.
05:33And our histogram is ready.
05:36We can read our histogram like,
05:39There are 5 people that have weight in the range of 100 to 125 pounds.
05:47There are 15 people in the range of 126 to 150 pounds.
05:56And so on.
05:58Now let's see what's the difference between histograms and bar graphs.
06:04In bar graphs, one axis shows the scale for numeric data,
06:09and the other one shows the textual data.
06:14Where bars are drawn and the height of bar relate to the numeric value that textual data holds.
06:22And there can be gap between the bars.
06:26Width of bars does not represent any value in bar graphs.
06:32Only the height of bars represents the quantity of textual data related to that bar.
06:39Now let's see histogram.
06:42In a histogram, one axis shows the scale of numeric data, like bar graph.
06:49And the other axis shows bars where the width of bars shows the class intervals.
06:56And there can be no gap between the bars in a histogram.
07:01And height of bar represent the quantity of that class interval that relate to the other information on other axes.
07:12That's same as a bar graph.
07:16So kids, we learned what's the difference between bar graphs and histograms.
07:23Now let's take a few more examples of histograms.
07:27Now we have another data.
07:30We have marks of all the students in grade 5.
07:34We cannot make a bar of each student as there are so many students.
07:40So we will make class intervals for categories of students.
07:46Students who have got marks in the range of 0 to 10.
07:50Students who have got marks in the range of 11 to 20.
07:56Similarly, categories for 21 to 30 marks.
08:0131 to 40 marks.
08:04And 41 to 50 marks.
08:07And we will make a bar for each class interval, rather than making a bar for each student.
08:15Now, let's answer a few questions.
08:19How many marks are there in the range of 0 to 10?
08:24There are 3 students in the range of 0 to 10.
08:29Similarly, count how many students have got marks in the range of 11 to 20.
08:37There are 7 students.
08:40Similarly, count for all categories.
08:45Now let's make a histogram out of it.
08:50We have two axes, like a bar graph.
08:55Let the title be Grade 5 Math Results.
09:00On y-axis, we will make a scale to show the frequencies or the number of data items in a particular class interval.
09:12On this scale, we will be showing the number of students who got marks in one particular class interval of marks.
09:21On x-axis, we will show the marks divided into class intervals.
09:28Number of students in different class intervals ranges from 1 to 20.
09:34First class interval is 0 to 10 marks.
09:39This category has 3 students, so make a bar up to the mark of 3 and label 0 to 10.
09:48Next class interval is 11 to 20 marks.
09:53This class interval or category has 7 students, so make a bar up to the mark of 7 and label it as 11 to 20.
10:06Next class interval is 21 to 30 marks.
10:11This category has 12 students, so make a bar up to the mark of 12 and label as 21 to 30.
10:22Next class interval is 31 to 40 marks.
10:28This category has 16 students.
10:32So make a bar up to the mark of 16 and label as 31 to 40.
10:39Next class interval is 41 to 50 marks.
10:43This category has 20 students, so make a bar up to the mark of 20 and label as 41 to 50.
10:54So our histogram is ready.
10:57We can read our histogram like 3 students got marks in the range of 0 to 10.
11:057 students got marks in the range of 11 to 20.
11:11And so on.
11:13So kids, today we have learned what is a histogram, how to make it and read it.
11:21Now you may go ahead and take a quiz to learn more.
11:25Bye-bye.