Grade 9 Statistics in Society worksheet
from Gradelings · Name: ______________________
How to explain it
- A sample is a smaller group chosen to stand for a whole population.
- A random, large sample is fairer. Bias happens when some people are left out.
- Data is reliable when you get similar results each time.
Example: A survey about school lunch asks only students in the cafeteria line. Is it fair? It leaves out students who do not buy lunch. That makes the sample biased. Answer: No, it is biased
Question 1
A school has 200 students. A survey asks 50 of them. What fraction of the students were surveyed? Type it in lowest terms.
answer box
1/4
Hint: Fraction = 50/200, which is 1/4 in lowest terms.
Question 2
In a random sample of 40 students, 16 said they walk to school. Based on this sample, about how many of 400 students walk?
answer box
160
Hint: The sample proportion is 16/40. Multiply by the population: 16/40 × 400 = 160.
Question 3
Four students report hours of sleep: 7, 8, 9, 8. What is the mean?
answer box
8
Hint: Add them: 32. Divide by 4: 8.
Question 4
Which is a primary source of data?
- a newspaper article about a survey
- a textbook summary
- an online comment
- a survey you conducted yourself
a survey you conducted yourself
Hint: Primary data is collected by you. Secondary data comes from someone else.
Question 5
A survey about screen time asks, “Don't you agree that too much screen time is harmful?” What is the problem?
- Nobody uses screens.
- The sample is too random.
- The question is too short.
- The question is leading and may bias the answers.
The question is leading and may bias the answers.
Hint: Fair questions use neutral wording that doesn't suggest the “right” answer.
Question 6
Which sample is most likely to represent all students at a school?
- 50 students chosen at random from the school list
- 50 students who volunteered online
- the 50 students on the basketball team
- 50 students at the lunch table nearest the gym
50 students chosen at random from the school list
Hint: A random sample gives every student an equal chance to be chosen.
Question 7
Ice cream sales and sunburns both rise in summer. What can we conclude?
- Ice cream causes sunburn.
- Sunburn causes ice cream sales.
- They are related to the season, but one does not necessarily cause the other.
- Nothing is related.
They are related to the season, but one does not necessarily cause the other.
Hint: Correlation is not causation. A third factor, hot sunny weather, affects both.
Question 8
In statistics, the population is…
- the average of the data
- the number of questions
- the people who answered
- the whole group you want to learn about
the whole group you want to learn about
Hint: A sample is a smaller part of the population that you actually survey.
Question 9
A result is reliable if…
- many people liked it
- it was published online
- it was fast
- repeating the study gives similar results
repeating the study gives similar results
Hint: Reliability is about consistency. Validity is about measuring what you intend to measure.
Question 10
A school has 800 students. A survey asks 80 of them. What fraction of the students were surveyed? Type it in lowest terms.
answer box
1/10
Hint: Fraction = 80/800, which is 1/10 in lowest terms.
Answer key
- 1. 1/4
- 2. 160
- 3. 8
- 4. a survey you conducted yourself
- 5. The question is leading and may bias the answers.
- 6. 50 students chosen at random from the school list
- 7. They are related to the season, but one does not necessarily cause the other.
- 8. the whole group you want to learn about
- 9. repeating the study gives similar results
- 10. 1/10
Want more than 10 questions?
In Gradelings the questions change every time and adjust to your child, with hints and kind feedback.