Data Handling (Pie Charts)

PIE CHARTS

A pie charts is used to represent data. It shows how a complete set of data is divided up into various parts. It is also used to obtain informations.

We can use fractions or percentages to represent the various parts in a pie charts.

We can construct a pie charts.

Example : The following table shows the favorites fruit of five pupils.

Fruit	Number of pupils
Mango	2
Guava	3
Watermelon	4
Papaya	1

Step to be taken to construct a pie charts

1. Find the number of equal parts the circular fraction chart template should have.

    Total number of fruit is 10 (2+3+4+1), so the pie chart must be divided into 10 equal parts.

2. Colour with a different colour

    2 parts for pupils who like mango,

    3 parts for pupils who like guava,

    4 parts for pupils who like watermelon and

    1 part for pupil who like papaya.

3. Find the percentage of pupils for each fruit.

     

   a.   Mango = 2/10 X 100 = 20%

                    

b.      Guava = 3/10 X 100 = 30%

c.       Watermelon = 4/10 X 100 = 40%

d.      Papaya = 1/10 X 100 = 10%

4. Label the parts with fruits and percentages and give the pie chart a title.

*We can determine the frequency, mode, range, mean, maximum value and minimum value from a pie chart or another type of organising data.

frequency = kekerapan (bilangan atau nilai bagi satu kategori)
mode = kekerapan tertinggi (frequency tertinggi)
mean = purata (average)
max. value = kekerapan tertinggi (the highest frequency)
min. value = kekerapan terendah (the lowest frequency)
range = beza antara max value dengan min. value

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Exercise 

1. A survey was made to find the type of music that a certain group of young people liked in a city. Adjoining pie chart shows the findings of this survey.

From this pie chart answer the following:

(i) If 20 people liked classical music, how many young people were surveyed?

Answer: When 10 people liked classical music, number of people surveyed is 100

So, When 1 person liked the classical music, number of people surveyed is

When 20 people like the classical music, number of people surveyed

(ii) Which type of music is liked by the maximum number of people?

Answer: Light music is liked by maximum number of people.

(iii) If a cassette company were to make 1000 CD’s, how many of each type would they make?

Answer: Number of CD’s for different music

Semi Classical = 1000 x 20% = 200

Classical = 1000 x 10% = 100

Folk = 1000 x 30% = 300

Light = 1000 x 40% = 400

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2. A group of 360 people were asked to vote for their favourite season from the three seasons rainy, winter and summer.

(i) Which season got the most votes?

(ii) Find the central angle of each sector.

(iii) Draw a pie chart to show this information.

Answer:
(i) Winter got the most number of votes.

(ii) Central Angle can be calculated as follows:

(iii) Pie Chart is as follows:

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3. Draw a pie chart showing the following information. The table shows the colours preferred by a group of people.

Calculate respective proportion of each colour and use that proportion to find the central angle.

Answer: Following is the required pie chart:

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4. The adjoining pie chart gives the marks scored in an examination by a student in Hindi, English, Mathematics, Social Science and Science. If the total marks obtained by the students were 540, answer the following questions. All values are shown in degrees.

(i) In which subject did the student score 105 marks?

In the pie chart 70° is the angle for Math, so the student scored 105 marks in math.

(ii) How many more marks were obtained by the student in Mathematics than in Hindi?

Answer: The difference in central angle between Math and Hindi = 90°-70°=20°

(iii) Examine whether the sum of the marks obtained in Social Science and Mathematics is more than that in Science and Hindi.

Answer: Total of Angles of Social Science and Math = 80°+70°=150°

Total of Angles of Science and Hindi = 65°+90°=155°

It is clear that sum of marks obtained in Social Science and Math is less than that in Science and Hindi.

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5. The number of students in a hostel, speaking different languages is given below. 
    Display the data in a pie chart.

Answer: