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Calculations From
Data Displays

Master how to read bar graphs, tables, and pie charts to calculate totals, differences, and percents: essential skills for the SSAT.

SSAT Middle Level: Quantitative

What Are Data Displays?

A data display is any visual way of organizing numbers so you can see patterns, compare values, and answer questions quickly. On the SSAT you will meet three main types:

Bar Graphs
Use the height or length of bars to show amounts for different categories.
Tables
Organize data in rows and columns with exact numbers you can compute with.
Pie Charts
Show parts of a whole as slices of a circle, often labeled with percents.

Reading a Bar Graph

0 10 20 30 40 30 40 20 25 Mon Tue Wed Thu Day Books Sold

Reading a Data Table

Flavor Votes
Chocolate45
Vanilla30
Strawberry15
Mint10

The Three Core Calculations

Almost every SSAT data-display question asks you to do one of three things:

Total
Add values together: \( \text{Total} = a + b + c + \ldots \)
Difference
Subtract to compare: \( \text{Difference} = \text{larger} - \text{smaller} \)
Percent
Part out of whole: \( \text{Percent} = \dfrac{\text{part}}{\text{total}} \times 100 \)

The Percent Formula

$$ \text{Percent} = \frac{\color{#4ade80}\text{Part}}{\color{#818cf8}\text{Total}} \color{#fbbf24}\times 100 $$

Total vs. Difference

Feature Total Difference
OperationAdditionSubtraction
Question cue"How many altogether?""How many more / fewer?"
Formula\( a + b + c + \ldots \)\( \text{larger} - \text{smaller} \)
Result meaningCombined amountGap between two values

How to Solve Any Data Question

1
Read the question first. Identify what it asks: total, difference, or percent.
2
Locate the data. Find the correct bars, rows, or slices in the display.
3
Pull out the numbers. Write them down so you don't mix up values.
4
Calculate. Add for totals, subtract for differences, or use the percent formula.
5
Check your answer. Does it make sense? Estimate to verify.

Example 1: Finding a Total

0 5 10 15 20 25 8 12 15 20 Red Blue Yellow Green Favorite Color Students

Example 2: Finding a Difference

Sport Students
Soccer48
Basketball36
Tennis18
Swimming24

Example 3: Finding a Percent

Fiction 60 books Non-fiction 30 books Comics 10 books

Example 4: Combined Calculation

Month Rainy Days
March12
April18
May6

Example 5: Multi-Step Bar Graph

0 50 100 150 200 250 120 180 200 5th 6th 7th Grade Tickets Sold

Common Mistakes to Avoid

✕ Misreading the Scale
If the y-axis goes by 10s, a bar halfway between 20 and 30 is 25, not 2.5. Always check the axis labels.
✕ Forgetting the Total
For percent questions, you must find the total first. Dividing by only one category gives a wrong answer.
✕ Wrong Operation
"How many more" means subtract. "How many altogether" means add. Read the question carefully.

Summary of Key Skills

Skill Operation Key Words
Total \( a + b + c + \ldots \) "altogether", "combined", "in all"
Difference \( \text{larger} - \text{smaller} \) "more than", "fewer", "how many left"
Percent \( \dfrac{\text{part}}{\text{total}} \times 100 \) "what percent", "what fraction"
Average \( \dfrac{\text{total}}{\text{number of items}} \) "average", "mean"

Question 1 of 5

How many pets do the students own in total?

Question 2 of 5

How many more tickets were sold on Saturday than on Friday?

Question 3 of 5

What percent of students chose Pizza?

Question 4 of 5

What percent of students either walk or bike to school?

Question 5 of 5

What is the average number of hours studied per subject?