Collecting & Organising Data — Worksheet & Memo

∑ DANEMATHICS

FREE CAPS MATHS RESOURCES

Grade 8 · Data Handling

Collecting & Organising Data

MEMORANDUM

Name:

Class:

Date:

Mark

/ 26

Answer all questions. Show all your working — marks are awarded for method as well as the final answer. Teacher copy: accept any correct equivalent method.

1
In a survey of 60 learners, 15 chose soccer as their favourite sport. Calculate the size of the soccer sector in a pie chart of the results.
(3)
15/60 of the learners chose soccer (1)
15/60 × 360° (1)
= 90° (1)✓✓✓ (3)
2
Is 'What is my height?' a statistical question? Why?
(2)
No — there is only one answer. A statistical question must have answers that vary.✓✓ (2)
3
Define a population in statistics.
(1)
The entire group being studied.✓ (1)
4
Why do we use a sample instead of the whole population?
(2)
It is faster and cheaper; asking everyone is usually impractical.✓✓ (2)
5
You survey only your friends about school food. What is wrong?
(2)
The sample is biased — it is not representative of the whole school.✓✓ (2)
6
What is wrong with the options '0–10, 10–20, 20–30'?
(2)
They overlap — 10 and 20 each fit two intervals.✓✓ (2)
7
In a stem-and-leaf display, what value is stem 4 with leaf 7?
(1)
47✓ (1)
8
Data: 12, 15, 21, 24, 28, 33. Write the stems.
(2)
Stems 1, 2, 3 (leaves: 2,5 | 1,4,8 | 3)✓✓ (2)
9
Tallies |||| |||| || represent what frequency?
(1)
12✓ (1)
10
In a survey of 60 learners, 25 chose soccer. Calculate the angle of the soccer sector in a pie chart.
(3)
25/60 × 360° ✓✓ = 150° ✓(3)
11
A pie chart of 90 learners has sectors of 120°, 100°, 80° and x. Calculate x and the number of learners it represents.
(3)
x = 360° − (120 + 100 + 80) = 60° ✓✓; 60/360 × 90 = 15 learners ✓(3)
12
State TWO features a double bar graph must have.
(2)
A key/legend showing what each colour means ✓; one shared vertical scale for both groups, with the pair of bars touching and gaps between categories ✓(2)
13
Why would a pie chart be the WRONG choice for data where learners could pick more than one sport?
(2)
The categories then overlap and do not add up to one whole ✓; a pie chart can only show parts of a single total, so a bar graph should be used ✓(2)

TOTAL: 26 marks