Distribution
What is a discrete random variable?
A variable that takes countable values
What shape does a normal distribution have?
Bell-shaped
Middle value
median
What is a confidence interval used to estimate in statistics?
It is used to estimate a range of values for a population parameter
Can a probability ever be negative?
no
A measure of how many standard deviations a value is from the mean
What is a z-score?
The central value of a data set
mean
What does a 95% confidence level mean in simple terms?
It means that if we repeated the study many times, about 95% of the intervals would contain the true population value.
What does P(x) represent in a probability distribution?
The probability that x occurs
In a normal distribution graph, where is the mean located?
At the center of the graph
How spread out the numbers are
standard deviation
What are the two main parts of a confidence interval formula?
The sample statistic (like sample mean) and the margin of error.
What does the expected value describe in simple terms?
The average outcome over many trials
What are the percentage of data within 1, 2, and 3 standard deviations?
68
95
99.7
Determine the median (1,2,5,7,9,9,9,11.13)
9
What happens to the width of a confidence interval when the sample size increases?
The interval becomes narrower (more precise).
What does the expected value represent in a discrete probability distribution?
mean outcome
A normal distribution has a mean of 70 and a standard deviation of 5. About 95% of the data fall between these two
Between 60-80
State the mean (70,75,80,85,90)
80
A sample mean is 80 with a margin of error of 5. What is the confidence interval?
80 ± 5 → (75, 85)