Pie Charts (DI)

The “pie chart” is also known as a “circle chart”. A pie chart is a type of graph that represents the data in the circular graph. A pie chart is a circular shaped chart, as the name suggested, it is like a pie divided into multiple sectors or slices to represent numerical data. In a pie chart, the length of the arc or central angle is proportional to the quantity that it represents.

Some importat point related to Pie Charts:

  • A Pie chart uses a circle to represent data.
  • Circle is divided into sectors representing different categories.
  • Angle of each sector is proportional to value of parameter.
  • Sum of angles of all sectors equals 360° which corresponds to total value of parameter.
  • Only one parameter can be plotted on one circle. Normally, used to represent segment-wise share or break-up of total quantity.Hence, not suitable for representing all type of data.
  • Simple to interpret and visually very appealing.

Conversion for Pie chart calculations:

The pie chart formula is given as

(Given Data/Total value of Data) × 360°

For example, a sector representing 20% of total quantity would have an angle of 15×3600720

Example : 

The following pie-charts show the distribution of students of graduate and post-graduate levels in seven different institutes in a town.

Distribution of students at graduate and post-graduate levels in seven institutes:

 

Question : 

What is the total number of graduate and post-graduate level students is institute R?

Solution

Required number = (17% of 27300) + (14% of 24700)
  = 4641 + 3458
  = 8099.

 

Question : 

What is the ratio between the number of students studying at post-graduate and graduate levels respectively from institute S?

Solution

Required ratio = (21% of 24700) = (21 x 24700) = 19 .
(14% of 27300) 14 x 27300 14

 

Example : 

The circle-graph given here shows the spendings of a country on various sports during a particular year. Study the graph carefully and answer the questions given below it.

Question: 

What percent of total spending is spent on Tennis?

Solution: 

Percentage of money spend on Tennis = ( 45 x 100 ) % = 12 1 %.
360 2

Question : 

How much percent less is spent on Football than that on Cricket?

Solution: 

Let the total spendings on sports be Rs. x. Then,

Amount spent on Cricket = Rs. ( 81 x x ) = Rs. 9x .
360 40
Amount spent on Football = Rs ( 54 x x ) = Rs. 3x .
360 20
Difference = Rs. ( 9x - 3x ) = Rs 3x .
40 20 40
Therefore Required percentage = Rs. ( ( 3x/40 ) x 100 ) % = 33 1 %.
9x/40 3