5.4    CIRCLE GRAPH OR PIE CHART

If we represent the data in a circle form then it is said to be a pie chart. This graph shows the relationship between the whole and its part. We have to divide the circle into sectors and each sector is proportional to its respective activity.

We use it when we have information on percentage or fraction.

Drawing of a Pie Chart:

If we have the information in percentage then we need to calculate the respective angles to show them in the pie chart.

As we know that a complete circle is of 360°, so we need to calculate the fraction of 360° for every sector.

Example:

Draw a pie chart of the following percentage of genres of movies liked by the public.

By using these angles draw a pie chart.

Exercise 5.2

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.

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

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

make.

Solution: (i) 10% represents 100 people.

⟹20% represents    =    (100×20) / 10    =    200

∴, 200 people were surveyed.

(ii) Since 40% of the total people surveyed liked light music and no other form of song liked more than that, we can conclude that Light music is liked by the maximum number of people.

(iii) CD’s of classical music    =    (10 × 1000) / 100    =    100

CD’s of semi  –  classical music    =    (20 × 1000) / 100    =    200

CD’s of light music    =    (40 × 1000) / 100    =    400

CD’s of folk music    =    (30 × 1000) / 100    =    300

1. A group of 360 people were asked to vote for their favorite 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

Solution: (i) According to the table given in the question, Winter season got the most votes.

(ii) Central angle of summer season   =    (90×360) / 360   =    900

Central angle of rainy season               =    (120×360) / 360   =    1200

Central angle of winter season            =    (150×360) / 360   =    1500

(iii)

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

Solution:Here, central angle    =    3600 Total number of people    =    36

1. 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.

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

(Hint: for 540 marks, the central angle    =    360°. So, for 105 marks, what is the central angle.)

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

(iii) Examine whether the sum of the marks obtained in Social Science and Mathematics is more than that in Science and Hindi. (Hint: Just study the central angles).

Solution:

(i) The student scored 105 marks in Hindi.

(ii) Marks obtained in Mathematics    =    135 Marks obtained in Hindi    =    105 Difference    =    135 – 105    =    30

Thus, 30 more marks were obtained by the student in Mathematics than in Hindi.

(iii) The sum of marks in Social Science and Mathematics    =    97.5   +   135    =    232.5 The sum of marks in Science and Hindi    =    120   +   105    =    225

∴, the sum of the marks in Social Science and Mathematics is more than that in Science and Hindi.

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

Solution:

1. Draw a pie chart of the data given below. The time spent by a child during a day.

Sleep — 8 hours ,School — 6 hours,Home work — 4 hours

Play — 4 hours,Others — 2 hours.

1. On a particular day, the sales (in rupees) of different items of a baker’s shop are given below. Draw a pie chart for this data.