Data Collection & Sampling
Is asking all students in a school about their opinion on uniforms a census or a survey?
Census
Convert 9:00 am into 24-hour time.
What does the steepness of a line represent in a distance–time graph?
The speed — steeper means faster.
What type of error happens when someone records 41 instead of 14 hours?
A processing error.
A pelican flies for 6 hours at 75 km/h. How far does it travel?
Why might a school choose to survey 50 out of 1000 students instead of everyone?
It saves time and resources; surveying everyone would be impractical.
You arrive at 7:48 am for a 9:00 am interview. How early are you?
1 hour 12 minutes early
In a bar graph showing the number of books read per student, what does each bar’s height represent?
The frequency or number of books read.
A survey about school uniforms is given only to Year 12 students. What’s the main issue with this data collection method?
The sample is not representative — it excludes other year levels, creating age or group bias.
The capacity of a pool should be measured in which unit?
Kilolitres (kL)
Surveying every 10th student on the roll — what sampling method is this?
Systematic sampling
A flight leaves Brisbane at 08:35 and lands in New Zealand at 13:55 (same time zone). How long is the flight?
5 hours 20 minutes
In a line graph showing temperature over a day, what does a horizontal line between 2 pm and 4 pm mean?
The temperature stayed constant during that time.
Why is a survey of only online customers for a shoe store about shopping habits biased?
It excludes people who shop in-store — sample not representative.
Jeffery’s heart rate: 72 → 80 → 140 → 168 → 174 bpm over 4 minutes. What type of graph is best to show this data? Provide two reasons why.
Line Graph - easy to read, useful for continuous numerical data.
State one advantage and one disadvantage of convenience sampling.
✅ Advantage: Quick and easy to collect data.
❌ Disadvantage: Biased and not representative of the population.
Which unit best measures the distance of a marathon?
Kilometres (km)
In a step graph, what does a filled-in dot represent?
It means that the value it lies on is included in that interval.
If only 250 out of 1000 people reply to a survey, what’s the issue?
Non-response bias — results don’t reflect the whole group.
A car travels 180 km in 3 hours. What is its average speed?
Speed = distance / time = 180÷3= 60 km/h
What’s wrong with this question: “Do you exercise regularly and eat healthy food?” How can it be improved?
It’s a double-barrelled question (asks two things).
Improved: Split into two separate questions — one about exercise, one about diet.
On a map, Brisbane to Bribie Island is 6.5 cm. Scale is 1 : 2,000,000. Find the real distance (km).
7.5 cm × 2,000,000 = 15,000,000 cm = 150 km
If a graph has the title “Rainfall Over a Week” and the vertical axis is labelled “Millimetres,” what would the horizontal axis likely be labelled?
Time or Days in the week.
Why does a non-representative sample make survey results unreliable?
Because it doesn’t reflect the population’s true characteristics, leading to biased conclusions.
A rectangular garden is 12 m long and 8 m wide. What is its perimeter?
2(12+8)= 40 m