Pie charts are simplest of all pictorial forms of data presentation. In Pie charts, the given data is distributed over a total angle of 360o, which is a complete circle. Here the data is presented only with respect to only one parameter. The shares of various elements is represented as a proportion or percentage of the total quantity.
In a pie chart, the various ‘Slices’ (Sectors) of the ‘Pie’ (Circle) is generally represented in one of the two forms, which are:
- Numerical values
- Percentage values
The total pie chart subtends an angle of 360o about its centre. This 360o cater to 100% of the quantity mentioned.
Let's solve an example to understand Pie charts:
Answer the following questions based on the given graphs.
Cardholders (%) Card Spends (%)
The number of cardholders in 2006 was 8.5 million, while card spendings amounted to Rs 64 crore.
1) What is the difference between the number of people who own Citibank cards and Bank of India cards (in millions)?
a) 72 b) 1.5 c) 2.5 d) 3
From the first pie chart, the difference in the percentage of cardholders of Citibank and Bank of India is 38 - 6 = 32%. Total no. of people = 8.5 million.
Therefore, the difference between both the cardholders is,
= 32 x 8.5/100
Hence, option (a) is correct.
2) If the owners of Cancard (Canara Bank’s) do not own any other card, what is their actual number?
a) 5 b) 6. 8 c) 6.5 d) 8
Canara bank has a cardholder percentage of 8, then their number is, 8 x 8.5/100 = 0.68 million = 6.8 lakh members.
Hence, option (b) is correct.
3) If card efficacy is defined as that percentage of the total purchase which is made through cards by card holders and if the Bank of Baroda card has a 30% efficacy in 2006, what is the approximate amount of purchase (in Rs crore) made by Bank of Baroda card holders during the year 2006? (Assume that Bank of Baroda card holders do not own any other credit cards)
a) 65 b) 22.7 c) 25.6 d) 30
Of the 64 crores of total card spending, Bank of Baroda accounts for 12%, it is, = 0.12x64.
Card efficacy = 30%, for every 100 spent, Rs.30 is spent by using the card. So, the total purchase is = 0.12x64x100/30 = Rs.25.6 crore
Hence, option (c) is correct.
4) If 30% of the spendings by the others category is by Big card, what is the amount accounted for by the remaining cards of others category? (In crore)
a) 2 b) 15.3 c) 12.5 d) 11.2
Since bigcard accounts for 30%, the remaining cards account for 70% of the others, which accounts for 25% of the Rs.64crore spendings. So 0.7x0.25x6.4 = 11.2crore.
Hence, option (d) is correct.