probability
What is the probability of flipping heads on a fair coin?
0.5
What type of graph is best for showing parts of a whole?
Pie chart
What is a sample?
A smaller group selected from a population.
What does a confidence interval estimate?
A population parameter
What is the mean of 4, 6, 10?
(4+6+10)/3 = 20/3
≈ 6.67
A bag has 3 red, 2 blue, and 5 green marbles. What is P(red)?
3/10
A histogram shows most values clustered on the left with a long tail to the right. What is the distribution?
Right‑skewed
What type of sampling gives every person an equal chance of being chosen?
Simple random sampling
A 95% confidence interval means what?
We are 95% confident the true population value lies in the interval.
What is the median of 2, 5, 7, 9, 12?
7
Two dice are rolled. What is the probability of getting a sum of 7?
6/36 = 1/6
In a boxplot, what does the line inside the box represent?
The median
A survey only asks students in a library. What type of bias is this?
Convenience bias
A sample mean is 50 with a margin of error of 4. Give the Confidence interval
(46, 54)
What is the mode of 3, 3, 4, 5, 6?
3
A spinner has 8 equal sections numbered 1–8. What is P(even number)?
4/8 = 1/2
A scatterplot shows points trending upward. What type of correlation is this?
Positive correlation
What is the difference between a parameter and a statistic?
Parameter = population value
statistic = sample value
What is the null hypothesis?
A statement that there is no effect or no difference.
Find the range of 12, 15, 22, 30
30 − 12
= 18
A class has 12 girls and 8 boys. Two students are chosen without replacement. What is P(boy then girl)?
(8/20) × (12/19) = 96/380 = 24/95
A dataset has an outlier far above the rest. How does this affect the mean?
It increases the mean more than the median.
A school wants to survey students by grade level. They randomly select 10 students from each grade. What sampling method is this?
Stratified sampling
A hypothesis test gives a p‑value of 0.01. What conclusion can be made at α = 0.05?
Reject the null hypothesis.
A dataset has a mean = 20 and a standard deviation = 4. What z‑score corresponds to x = 28?
z = (28 − 20) / 4
= 2