Collect, Organise & Summarise Data (Grade 9) — Worksheet & Memo

∑ DANEMATHICS

FREE CAPS MATHS RESOURCES

Grade 9 · Data Handling

Collect, Organise & Summarise Data (Grade 9)

MEMORANDUM

Name:

Class:

Date:

Mark

/ 18

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
What is the difference between a population and a sample?
(2)
The population is the whole group; the sample is the smaller part actually surveyed.✓✓ (2)
2
Why is surveying only your friends about school food biased?
(2)
They are not representative of the whole school.✓✓ (2)
3
What is wrong with the intervals 0–10, 10–20, 20–30?
(2)
They overlap — 10 and 20 each fit two intervals.✓✓ (2)
4
How do a histogram and a bar graph differ?
(2)
Histogram bars touch (continuous data); bar-graph bars have gaps (separate categories).✓✓ (2)
5
In the histogram above, which is the modal class?
(2)
20–29, with a frequency of 9✓✓ (2)
6
In the histogram above, how many values are there in total?
(2)
3+7+9+5+2 = 26✓✓ (2)
7
Find the mean of R8 000, R9 000, R9 500, R10 000 and R80 000.
(2)
116 500 ÷ 5 = R23 300✓✓ (2)
8
Find the median of that same salary data.
(2)
R9 500✓✓ (2)
9
Which average is fairer for that salary data, and why?
(2)
The median — the R80 000 outlier pulls the mean far above what almost everyone earns.✓✓ (2)

TOTAL: 18 marks