WBBSE Solutions For Class 8 Maths Arithmetic Chapter 2 Pie Chart

Arithmetic Chapter 2 Pie Chart

A pie chart is a circular statistical graphic which is divided into slices to illustrate numerical proportions.

In a pie chart, the arc length of each slice is proportional to the quantity it represents.

In pie chart values of various datas of components are represented by sectors of a circle. The angle at the centre of the sector gives the value of the data.

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At the centre, a circle makes a complete angle i.e. 360°.

Centre angle for a data = \(\left(\frac{\text { Value of the data }}{\text { Total value }} \times 360\right)^{\circ}\)

Method of drawing of Pie Chart:

1. Compute the central angles for the given datas using the above formula.
2. Draw a circle with any radius.
3. Divide the interior of the circle into different sectors having the angles as obtained (1) with the help of protractor.
4. Lable the sections properly to obtain the required pie chart.

Arithmetic Chapter 2 Pie Chart Examples

Example 1. There are 100 students in your class. The following table shows their hobby.

Draw a Pie Chart for the given data.

Solution:

Process:

Draw a circle with any radius (OA).

The central angle of the sector which represents the travel is 36°. So I draw ∠AOB 36° with the help of a protractor.

Now, I draw the sectors by reversing the protractor, the central angles of which are 18°, 216° and 90° respectively.

Thus I made a pie chart of the data.

Example 2. Arpita have made a model. She made a chart of expenditures of buying materials.

Make a pie chart with this information and write the central angle of the sectors.

Solution:

Example 3. The pie chart of what kind of programmes Information News the audience likes:

1. Write How many parts of the total circular region is the sector of the audience who watch news in the pie chart?
2. Write what kind of programme gets the most audience.
3. Write what kind of programme gets the least audience.
4. Write how many parts of the total audience watch the programmes of sports?

Solution:

1. No. of parts of total circular region is the sector of the audience who watch news in the pie chart is \(\frac{20}{360}\) or \(\frac{1}{18}\)
2. Entertaining programmes gets the most audience. [Entertained is 240°]
3. Informative programme gets the least audience.
4. \(\frac{90}{360}\) or \(\frac{1}{4}\) parts of the total audience watch the programmes of sports.

Example 4. Choose the correct Answer:

1. Pie Chart is also known as

1. Circle graph
2. Histogram
3. Bar graph
4. None of these

Answer: 1. Circle graph

2. Central angle for data

1. \(\frac{\text { Total value }}{\text { Value of the data }} \times 360^{\circ}\)
2. \(\frac{\text { Value of the data }}{\text { Total value }} \times 360^{\circ}\)
3. \(\frac{\text { Value of the data }}{\text { Total value }} \times 100^{\circ}\)
4. None of these

Answer: 2. \(\frac{\text { Value of the data }}{\text { Total value }} \times 360^{\circ}\)

3. A survey was made to find of music lovers like. If 20 people like classical music the number of people surveyed is

1. 100
2. 200
3. 50
4. 10

Answer: 2. 200

Example 5. Fill in the blanks:

1. Pie chart is also known as _______ graph.

Answer: Circle chart.

2. Study the following table below:

Measurement of central angle of Santro is ________

Solution: Measurement of central angle of santro is \(\left(\frac{6}{36} \times 360^{\circ}\right)=60^{\circ}\)

Answer: 60°

Example 6. Write ‘True’ or ‘False’.

1. Pie chart is a bar graph.

Answer: False

2. The whole circle represents the sum of the value of the components.

Answer: True