GMAT Data Insights

GMAT data insights table analysis practice

Data Insights tests how well you read tables and graphs and decide what the data supports. The calculations are usually short, but you must choose the right base for each percentage. Here are two original tables with four questions each.

Key ideas

Read the title, units and column headings before looking at the numbers.
Decide whether a question asks for a share, a change or a ratio, and use the correct base.
A simple average of percentages is wrong when the groups have different sizes.
Estimate first. Many answer choices are far apart.

Common traps

Dividing by the wrong year when calculating percent change.
Using a simple average of percentages instead of a weighted average.
Confusing a quarter with the highest share and the quarter with the highest value.

Two data tables

Table 1: Quarterly revenue by product line (₹ lakh)

Product line	Q1	Q2	Q3	Q4
Laptops	120	135	150	165
Phones	200	180	210	260
Tablets	90	95	80	110
Wearables	40	55	70	95
Accessories	60	65	70	75

Table 2: City survey

City	Population (lakh)	Residents who own a car (%)	Commuters who use public transport (%)
Arden	12	35	50
Bexley	8	28	60
Corvin	15	40	35
Dunmere	6	22	65
Elston	10	30	55
Falmore	20	45	30

Practice questions with solutions

Try each question first, then open the solution. Time yourself and note where you hesitate.

Table 1: Which product line had the highest total revenue over the four quarters?
- A Wearables
- B Accessories
- C Laptops
- D Tablets
- E Phones
Show answer and solution

Answer: E. Phones

Totals: Laptops 570, Phones 850, Tablets 375, Wearables 260, Accessories 270. Phones is highest.
Table 1: Wearables revenue in Q4 was what percent higher than in Q1?
- A 95%
- B 137.5%
- C 55%
- D 237.5%
- E 57.9%
Show answer and solution

Answer: B. 137.5%

(95 - 40) / 40 = 55 / 40 = 1.375, which is 137.5%. Dividing by the Q4 value would give a wrong 57.9%.
Table 1: In which quarter did Phones account for the largest share of total revenue?
- A Q3
- B Q4
- C Q2
- D The share was the same in every quarter
- E Q1
Show answer and solution

Answer: E. Q1

Shares: Q1 200/510 = 39.2%, Q2 180/530 = 34.0%, Q3 210/580 = 36.2%, Q4 260/705 = 36.9%. Q1 is highest, even though Q4 had the highest phone revenue.
Table 1: By how many ₹ lakh did total revenue in Q4 exceed total revenue in Q1?
- A 175
- B 225
- C 185
- D 195
- E 205
Show answer and solution

Answer: D. 195

Q4 total = 165 + 260 + 110 + 95 + 75 = 705. Q1 total = 120 + 200 + 90 + 40 + 60 = 510. The difference is 195.
Table 2: Taking the percentages to apply to each city's whole population, how many lakh residents of Arden and Elston together own a car?
- A 6.0
- B 7.2
- C 7.5
- D 9.6
- E 8.4
Show answer and solution

Answer: B. 7.2

Arden: 12 x 35% = 4.2 lakh. Elston: 10 x 30% = 3.0 lakh. Together 7.2 lakh.
Table 2: Which city has the highest ratio of public transport use (%) to car ownership (%)?
- A Bexley
- B Elston
- C Arden
- D Falmore
- E Dunmere
Show answer and solution

Answer: E. Dunmere

Ratios: Arden 1.43, Bexley 2.14, Corvin 0.88, Dunmere 2.95, Elston 1.83, Falmore 0.67. Dunmere is highest.
Table 2: What is the combined population, in lakh, of the cities in which more than 50% of commuters use public transport?
- A 30
- B 24
- C 18
- D 34
- E 14
Show answer and solution

Answer: B. 24

Cities above 50% are Bexley (60), Dunmere (65) and Elston (55). Arden is exactly 50, so it is not included. 8 + 6 + 10 = 24.
Table 2: Taking the percentages to apply to each city's whole population, what is the approximate share of car owners across all six cities combined?
- A 33%
- B 40%
- C 36%
- D 35%
- E 38%
Show answer and solution

Answer: C. 36%

Car owners in lakh: 4.2 + 2.24 + 6.0 + 1.32 + 3.0 + 9.0 = 25.76. Population: 71. 25.76 / 71 = 36.3%. The simple average of the six percentages is 33.3%, which is not correct because the cities differ in size.