Data Handling (Including Pictograph and Bar Graph)
ICSE Class 6 · Mathematics · Chapter 33
What this chapter covers
- Collecting data
- Organising data: tally marks and frequency tables
- Pictographs
- Bar graphs
- Choosing how to show data
Key points
- Data are facts, such as numbers or names, collected to give information.
- Data can be collected to test a hypothesis, which is a guess.
- Raw data is unarranged; organising it makes it easy to read.
- Tally marks are drawn in groups of five, with the fifth stroke across the first four.
- Frequency is how many times an item occurs. The total of the frequencies equals the number of observations.
- A pictograph uses symbols. Its key tells how many items one symbol stands for.
- A bar graph uses bars of equal width with equal gaps. The length of a bar shows its value.
- Always read the title, key or scale before reading any graph.
Questions answered
What is raw data?
Raw data is data just as it was collected, before it is arranged in any way.
In a tally, how is the number 12 shown?
Two groups of five and two single strokes: IIII/ IIII/ II.
The frequency of "red" in a survey of favourite colours is 6. What does that mean?
Six people chose red as their favourite colour.
In a pictograph, one symbol stands for 20 kites. How many kites do 4 and a half symbols stand for?
4 × 20 + 10 = 90 kites.
Why must every pictograph have a key?
Without the key, the reader cannot tell how many items one symbol stands for.
On a bar graph, 1 cm stands for 5 students. How tall is the bar for 35 students?
35 ÷ 5 = 7, so the bar is 7 cm tall.
Meera says her bar for 80 should be wider than her bar for 40. Is she right?
No. All bars have the same width. Only the length shows the value.
Sana guesses that more children in her class have a sister than a brother. How can she test this?
She can ask each classmate, record the answers with tally marks, make a frequency table and compare the two frequencies.