What is a population in statistics? — The entire group being studied.The population is the entire group you want to study. A sample is a smaller subset selected from the population.
What is a sample? — A subset of the population selected for study.A sample is a subset of the population that is selected and studied to make inferences about the whole population.
Which type of sample best represents the entire population? — Random sample.A random sample gives every member of the population an equal chance of selection, which reduces bias and produces valid inferences.
A random sample of 30 students from a school of 600 shows 18 prefer math. About how many of the 600 students prefer math? — 360.18/30 = 60%. 600 × 0.60 = 360 students.
Which is an example of a biased sample? — Surveying only students who volunteered to participate.Volunteers are self-selected — those who choose to participate may have stronger opinions, creating bias.
Why do we use samples instead of studying the entire population? — Studying the entire population is often impractical or impossible.Studying every member of a large population is usually too costly, time-consuming, or impractical.
A valid inference from a random sample can be applied to: — The entire population it was drawn from.Inferences based on a random sample are valid for the population from which the sample was drawn.
Which measure of center is found by adding all values and dividing by the number of values? — Mean.The mean (average) = sum of all values ÷ number of values.
Which measure of center is the middle value when data is ordered from least to greatest? — Median.The median is the middle value in an ordered data set (or the average of the two middle values if even count).
What does MAD stand for? — Mean Absolute Deviation.MAD = Mean Absolute Deviation. It measures the average distance of data points from the mean.
IQR stands for: — Interquartile Range.IQR = Interquartile Range = Q3 − Q1. It measures the spread of the middle 50% of the data.
Two classes have means of 82 and 79. Which has the higher "typical" score? — The class with mean 82.A higher mean indicates a higher typical score. The class with mean 82 scores higher on average.
Class A has range 10; Class B has range 30. Which is more consistent? — Class A, smaller range means less variability.A smaller range means data values are closer together — Class A is more consistent.
A complete comparison statement for data sets says: — Group X typically scored [higher/lower] AND had [more/less] variability.A complete comparison statement addresses both center (typical score) and spread (consistency/variability).
A data set with low variability means: — Data values are clustered near the center.Low variability (small spread) means data values are tightly clustered around the center.
Probability is always between which two values? — 0 and 1.Probability ranges from 0 (impossible) to 1 (certain). It can also be expressed as a percent from 0% to 100%.
A bag has 5 red and 5 blue marbles. What is the probability of drawing a red marble? — 1/2.P(red) = 5/10 = 1/2. Equal numbers means equal probability.
A standard die has 6 faces. What is the probability of rolling a 4? — 1/6.P(rolling 4) = 1/6. There is 1 favorable outcome out of 6 equally likely outcomes.
A spinner has 4 equal sections: red, blue, green, yellow. What is P(landing on blue)? — 1/4.P(blue) = 1/4. Each of the 4 equal sections has probability 1/4.
What is the probability of an impossible event? — 0.An impossible event has probability 0 — it can never happen.
What is the probability of a certain event? — 1.A certain event always happens, so its probability is 1 (100%).
An event has P = 0.75. What is the probability it does NOT occur? — 0.25.P(complement) = 1 − 0.75 = 0.25.
You roll a die. What is P(odd number)? — 1/2.Odd numbers on a die: 1, 3, 5 — that's 3 out of 6. P(odd) = 3/6 = 1/2.
What is P(rolling a number greater than 4 on a standard die)? — 1/3.Numbers greater than 4: 5, 6 — that's 2 out of 6. P = 2/6 = 1/3.