Bigger bar charts and rounding · Usually met around P4
Making bar charts with big scales
Choose the smallest scale that fits the biggest value.
How to do it
Method
Choose the smallest scale that fits the biggest value
Biggest 380: 10 × 50 = 500 ≥ 380, choose 50
Another way
Try and adjust
10 × 20 = 200 is too small; use 50
In full
To make a bar chart, sort the data and count each kind into a frequency table; the counts should add up to the total. Then choose what a square stands for: with 10 squares up the side, take the smallest scale that still fits the biggest value. Biggest 380: 20 a square only reaches 200, 50 a square reaches 500, so choose 50. If data doesn't land on a line, round it first: at 100 a square, 1260 becomes 1300, so draw 13 squares. Or try a scale, multiply it by 10 to see if it fits, and adjust.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
Each square on a bar chart stands for 100. The value 890 is first rounded to the nearest hundred. How many squares high is the bar?
Show the answer and working
Answer: 9 squares
890 rounds to 900, and 900 ÷ 100 = 9 squares.
Example 2
The biggest value in some data is 472. A bar chart has 10 squares up the side. What should each square stand for?
- A. 100
- B. 20
- C. 1
- D. 50
Choose the right answer
Show the answer and working
Answer: D. 50
Take the smallest that fits 472: 10 × 50 reaches 472.
Example 3
The favourite fruit of 15 friends: 🍓🍓🍌🍓🍎🍎🍎🍓🍎🍎🍓🍓🍎🍓🍎. As a frequency table: 🍎 □, 🍓 □, 🍌 □.
Fill in each box
Show the answer and working
Answer: 7，7，1
Count each kind: 7, 7, 1; they add to 15, so the count is right.
Practise it in the game →Bigger bar charts and rounding · Free to start, unlimited questions, no download