Lesson 7.2 · Data
Answering questions about data
You made a chart. Now it is time to use it! A chart can answer lots of questions, like "Which snack won?" and "How many more kids chose apples?"
Four kinds of questions
Here is a picture graph about favorite ice cream.
| Flavor | Number of kids |
|---|---|
| Chocolate | 🍫 🍫 🍫 🍫 🍫 🍫 🍫 |
| Vanilla | 🍦 🍦 🍦 🍦 |
| Strawberry | 🍓 🍓 🍓 🍓 🍓 |
You can ask:
- How many in one group? Count one row. Vanilla has 4.
- Which is most or least? Find the longest and shortest rows. Chocolate is the most. Vanilla is the least.
- How many in all? Add every row: kids.
- How many more or fewer? Compare two rows.
Add or subtract?
- "How many in all?" or "How many altogether?" means add the groups.
- "How many more?" or "How many fewer?" means subtract the smaller number from the bigger one.
Comparing two rows
To find how many more, line up the two rows. Match the pictures one to one. The extras have no partner.
- Chocolate: 🍫 🍫 🍫 🍫 🍫 🍫 🍫
- Vanilla: 🍦 🍦 🍦 🍦
Four chocolates have a partner. 3 chocolates are left over. So 3 more kids chose chocolate than vanilla. You can also subtract: .
Worked example: How many in all?
This tally chart shows the bugs Sam found.
- 🐜 Ant:
||||||| - 🐞 Ladybug: ||
- 🐛 Caterpillar:
||||
How many bugs did Sam find in all?
Ant is 8, ladybug is 2 and caterpillar is 5. Add them. Make a ten first: , then . Sam found 15 bugs.
Worked example: How many fewer?
Use Sam's chart. How many fewer ladybugs than caterpillars did he find?
Caterpillars: 5. Ladybugs: 2. Subtract: . Sam found 3 fewer ladybugs.
Worked example: Working backward
Some kids voted for a game. Tag got 6 votes. Hide-and-seek got 4 votes. Jump rope got the rest. There were 13 votes in all. How many votes did jump rope get?
Tag and hide-and-seek together: . The total is 13, so jump rope got votes. Check: . ✔️
Common mistake
"How many more" does not mean the bigger number. If cats have 9 and dogs have 5, cats do not have 9 more. They have more.
Practice
Use this picture graph for Problems 1 to 4. It shows the books kids read.
| Book | Number of kids |
|---|---|
| Animals | 📘 📘 📘 📘 📘 📘 |
| Space | 📗 📗 📗 |
| Sports | 📕 📕 📕 📕 📕 |
How many kids read a space book?
Type a number.
Which kind of book did the fewest kids read?
How many kids are in the graph in all?
Type a number.
How many more kids read about animals than about space?
Type a number.
Use this tally chart for Problems 5 and 6. It shows the weather for some days.
- ☀️ Sunny:
|||||||| - ☁️ Cloudy:
||||| - 🌧️ Rainy: ||||
How many more sunny days than cloudy days were there?
Type a number.
How many days are in the chart altogether?
Type a number.
A class voted on a pet. Fish got 4 votes. Bird got 3 votes. Hamster got the rest. There were 12 votes in all. How many votes did hamster get?
Type a number.