Pie Charts - SS2 Economics Lesson Note

Pie charts are a type of graphical representation that uses a circle to represent the total value and slices of the circle to represent the relative proportions of different categories.   

Applications of pie charts:

• Showing percentages: Pie charts are often used to show percentages of different categories in relation to the total value.

Comparing proportions: Pie charts can be used to compare the proportions of different categories.

Visualizing data: Pie charts can be used to visualize data in a way that is easy to understand.

Identifying patterns: Pie charts can be used to identify patterns in data, such as which categories are more or less common.

Making decisions: Pie charts can be used to make informed decisions, such as which category to focus on in order to improve performance.

 

Word Problems on Pie Charts:

1. A survey was conducted to find out the favourite pizza toppings of customers in a restaurant. 40% of customers prefer pepperoni,  25% of customers prefer mushrooms, 15% of customers prefer sausage,  10% of customers prefer onion and 10% of customers prefer green pepper. Use this data to formulate a pie chart

Solution:

Step 1: Identify the variable and categories: The variable is the "percentage" and the categories are the different types of pizza toppings: pepperoni, mushroom, sausage, onion, and green pepper.

Step 2: Calculate the angle of each sector: Multiply the percentage of each category by 360° to get the angle of each sector. For example, the angle for pepperoni = 40% x 360° = 144°.

Step 3: Draw a circle: Draw a circle to represent the pie chart.

Step 4: Draw the sectors: For each category, draw a sector in the circle with an angle equal to the angle calculated in Step 2. The sectors should be arranged in a clockwise order starting from the top.

Step 5: Label the chart: Title the chart as "Favourite Pizza Toppings." Label each sector with the corresponding category name and percentage.

A survey was conducted to find out the distribution of different types of mobile phones among a group of 1000 students. The following table shows the results of the survey: 35% of students use iPhone, 30% use Samsung, 15% use Xiaomi, 10% use Oppo and 10% use other types of mobile phones.

I. Formulate a pie chart to represent this data:

II. How many students use Oppo mobile phones?

Solution:

I. Step 1: Identify the variable and categories: The variable is the "percentage" and the categories are the different types of mobile phones: iPhone, Samsung, Xiaomi, Oppo, and Other.

Step 2: Calculate the angle of each sector: Multiply the percentage of each category by 360° to get the angle of each sector. For example, the angle for iPhone is 35% x 360° = 126°.

Step 3: Draw a circle: Draw a circle to represent the pie chart.

Step 4: Draw the sectors: For each category, draw a sector in the circle with an angle equal to the angle calculated in Step 2. The sectors should be arranged in a clockwise order starting from the top.

Step 5: Label the chart: Title the chart as "Distribution of Mobile Phones among Students." Label each sector with the corresponding category name and percentage.

II.To find the number of students who use Oppo mobile phones, we can use the percentage of students who use Oppo:

Percentage of students who use Oppo = 10%

We can then use this percentage to find the actual number of students:

Number of students who use Oppo = (Percentage of students who use Oppo / 100) x Total number of students

Substituting the values from the table, we get:

Number of students who use Oppo = (10 / 100) x 1000 = 100

Thus, 100 students use Oppo mobile phones.