Unit 7 Review - Probs & Stats

Why can't we use the Normal Model for confidence intervals or hypothesis tests involving sample means?

• Because the sample size is always large.

• Because the population mean is always known.

• Because the Normal Model is only for proportions.

• Because we have extra variability in sample means.

What is substituted for the population mean (μ) in sample means problems?

• p̂

• x̄

• σ

• p₀

What does a t-Distribution display?

• Standardized distances of sample means to the population mean.

• The exact population mean.

• The exact population standard deviation.

• The probability of a sample proportion.

What is the formula for the t-value in a t-Model?

• t = (x̄ - μ) / (σ/√n)

• t = (x̄ - μ) / (s/√n)

• t = (p̂ - p₀) / (σ/√n)

• t = (p̂ - p₀) / (s/√n)

What is the shape of a t-Distribution compared to a Normal Model?

• Skewed left

• Skewed right

• Bell shape, symmetric, with fatter tails

• Uniform distribution

What does "degrees of freedom" refer to in the context of t-Distributions?

• The number of parameters you are estimating

• The number of independent observations in a data set

• The number of dependent variables in a data set

• The number of total observations in a data set

What is the purpose of a confidence interval?

• To estimate the true population mean (μ)

• To find the exact population mean (μ)

• To determine the sample size

• To calculate the standard deviation

When should you use a 1-Sample T-Interval?

• When you know the population mean

• When the problem involves a categorical variable

• When you don't know μ, but you'd like to

• When the sample size is less than 10

What is the standard error (SE) in the context of sample means?

• The standard deviation of the population

• The standard deviation of the sample

• The standard deviation of our sample proportion or sample mean

• The mean of the sample

What distribution is used in confidence interval problems involving sample means?

• Normal Distribution

• Binomial Distribution

• t-Distribution

• Poisson Distribution