Reading Histograms

Why do you use a histogram?

Histogram is an illustrative way to represent a particular data. It is shown in vertical bar formation for a particular input and with respect to the number of continuous data given, which is said to be the frequency in each category.

A histogram is a single block graph of rectangles where the area of each rectangle will be proportional to the frequency.

reading histograms
reading histograms

 Example 1: The points scored by John in his school test was marked in 10 for subjects Math, English, Science, French as 5, 6, 8, 7 respectively. Represent the above data in a histogram.

reading histograms

Example 2: The following histogram shows the number of singers who sang music albums in a year. Find the following:

  1. Highest number of songs sung in a year.
  2. Least number of songs sung.
  3. of songs 14 singers sang.
  4. How many singers sang 3-4 songs?
reading histograms

In such a pictorial representation it is easy to identify and find out, calculate a specific detail instead of analyzing the whole data.

Solution:

  1. Grey colored bar on the graph states that 6 is the highest number of songs sung.
  2. Purple colored bar denotes 1 is least number of song sung.
  3. 5-6 songs were sung by 14 singers.
  4. 11 singers sang 3-4 songs.

Example 3: Following is the histogram view of a data showing the list of people who order home utilities online.

Basic items sold online are furniture, kitchen appliances, mobile phones and groceries.

  • Find the product that is sold largely.
  • How many people buy groceries online?
reading histograms

  Solution:

  • The product which is sold largely is kitchen appliances.
  • Between 0-200 people buy groceries online.

 

  1. Use the histogram to identify how long a student spends time on gadgets on school off days.

a.How many students spend only 5-10 hours?

b.How long does 4 students spend on gadgets?

c.Number of students spending maximum number of hours.

  1. Sheila collected the details of no. of novels sold in a book fair and made a histogram of the data which showed the no. of books sold between 20-200 dollars.

a) Draw a histogram if following is the data collected.

No. of books (novels)Amount (in Dollars)
2055
3080
4075
 50150
 6030
70105
80125

b) How many books were sold between $150 and $105?

Answer key
  1. 3 students
  2. 10 – 15 hours
  3. 9 students
    1. Histogram made by Sheila will look like:

b.20 books were sold between $105 and $150.