Pie chart DI for SBI PO

A pie chart divides one total into parts. On its own it is the easiest DI format, because every part is a fixed fraction of a known whole. That is why SBI PO-style sets rarely give a pie chart alone. They pair it with a table (say, the male-to-female ratio in each part) or with a second pie for a different year. The difficulty then lies in combining the two correctly.

This guide covers the conversions, a worked set of the pie-plus-table type, the one trap that catches most people (comparing shares across different totals) and a practice set. The pie values are given in tables because there are no images.

The conversions, and why they work

A full circle is 360° and represents 100% of the total. So:

• 1% = 3.6°, because 360 ÷ 100 = 3.6.
• Central angle = share % × 3.6.
• Share % = angle ÷ 3.6.
• Amount of a part = total × share % ÷ 100, or total × angle ÷ 360.

When the total is a friendly multiple of 360, the degree form is faster. With 3,600 employees, each degree is 10 employees, so a 108° sector is 1,080 people without any percentage step.

Question types and the step each needs

Most pie questions are one of these six. If a question seems to need more steps, check whether a simpler row applies before calculating amounts you don't need.

The worked set

A company has 3,600 employees. A pie chart shows their distribution across five departments in degrees, and a table gives the male-to-female ratio in each department. These are made-up figures for practice.

The angles add up to 360°, as they must. Build the working table first: employees = angle × 10, then split each by its ratio.

To split in a ratio, divide by the sum of the ratio parts. Operations: 1,080 ÷ 9 = 120, so 5 × 120 = 600 men and 4 × 120 = 480 women.

Q1. How many women work in the company?

• 180 + 270 + 480 + 270 + 300 = 1,500.

Q2. If a pie chart of only the female employees were drawn, what would be the central angle for Operations?

• 480 ÷ 1,500 × 360 = 115.2°.
• Note the base changes: this pie is out of 1,500 women, not 3,600 employees.

Q3. The number of men in Sales is what percentage more than the number of men in IT?

• (630 − 450) ÷ 450 × 100 = 180 ÷ 450 × 100 = 40%.

Q4. Next year IT grows by 25% and every new hire is a woman. What percentage of IT will then be women?

• New IT strength = 720 × 1.25 = 900. New hires = 180, all women.
• Women = 270 + 180 = 450, which is 450 ÷ 900 = 50%.

Q5. What is the ratio of men in Finance and HR together to women in Sales and IT together?

• Men: 240 + 180 = 420. Women: 270 + 270 = 540.
• 420 : 540 = 7 : 9.

The changing-total trap

When two pie charts show different years with different totals, a smaller share does not mean a smaller amount.

Suppose a bank's loan book is ₹2,400 crore with agriculture at 18%, and next year the book is ₹3,000 crore with agriculture at 15%. The share fell by 3 percentage points, but the amount went from ₹432 crore to ₹450 crore. It rose.

Speed habits

• Differences through the unit value. If 1% of the total is ₹24 crore, a 7-point gap between two heads is ₹168 crore in one step.
• Ratios straight from shares. Within one pie, the ratio of two parts equals the ratio of their percentages or angles. Retail 35% to corporate 20% is 7 : 4 without calculating either amount.
• Check that the pie adds up. Degrees should total 360 and percentages 100. If they don't, you have misread a value.

Practice set

A bank's loan book of ₹2,400 crore is split as follows. Made-up figures.

1. What is the amount lent to retail?
2. What is the central angle for MSME?
3. Next year the loan book grows to ₹3,000 crore and agriculture's share falls to 15%. By how much does the agriculture amount change?
4. Corporate and others together are what percentage more than agriculture, to two decimals?
5. What is the difference between the central angles of retail and corporate?
6. From the worked set: what percentage of the company's men work in Operations, to two decimals?

Answers:

1. ₹840 crore. 35% of 2,400.
2. 79.2°. 22 × 3.6.
3. Rises by ₹18 crore. 18% of 2,400 = 432; 15% of 3,000 = 450.
4. 38.89%. 25% against 18%: 7 ÷ 18 × 100 ≈ 38.89. Within one pie you can work with the shares directly.
5. 54°. The shares differ by 15 points, and 15 × 3.6 = 54.
6. 28.57%. 600 ÷ 2,100 × 100 = 2/7 ≈ 28.57.

What to do next

• Learn the share-to-angle table above until you can recall it instantly.
• Practise three pie-plus-table sets this week, always building the working table first.
• Try a set with two pies for two years and practise converting to amounts before comparing.
• Next, move to caselet DI, where you build the table from a paragraph. For weighted averages and "percent vs percentage points", see arithmetic inside DI.