Probability and Statistics Pretest

John Paul conducted a poll survey in which 320 out of 600 randomly selected voters indicated their preference for a certain candidate. He uses 95% confidence interval. What is the confidence interval estimate of the population proportion who prefer the candidate?

• 50% < p < 56%

• 48% < p < 58%

• 44% < p < 62%

• 42% < p < 64%

In a 99% confidence level with margin of error 0.20 and sample proportion 0.45, what is the sample size to be used?

• 41

• 42

• 43

• 44

A politician engaged the services of a private opinion pollster to determine the sample size needed among his constituents to interview about their perceptions on the freedom of information bill. Previous polls revealed that approximately 62% are in favor of the bill. The politician adopted 95% level of confidence and off the value of the population by at most 0.02. What should be the sample size?

• 1603

• 1604

• 2262

• 2263

• 10

• 1

• 0.1

• 0.01

Using the z table, what is the critical value when the level of significance a = 0.10 and it is a left-tailed test?

• 0.25

• 0.26

• 1.28

• 1.29

Smaller p-values indicate more evidence in support of:

• the null hypothesis

• the alternative hypothesis

• the quality of the researcher

• further testing

What is a random variable?

• A random variable is a variable that only takes on values from a specific set of outcomes.

• A random variable is a constant that represents a specific event in a process.

• A random variable is a fixed number that does not change.

• A random variable is a variable that takes on numerical values determined by the outcomes of a random process.

Define the sample space in a probability experiment.

• The sample space is the most likely outcome of an experiment.

• The sample space is the average of all outcomes.

• The sample space is the set of all possible outcomes of a probability experiment.

• The sample space is the sum of all possible outcomes.

Explain what a probability distribution is.

• A probability distribution is a fixed set of outcomes that cannot change.

• A probability distribution is a method to calculate the average of a dataset.

• A probability distribution is a graphical representation of data points.

• A probability distribution is a function that describes the likelihood of different outcomes for a random variable.

What is the shape of a normal curve?

• Triangular and uneven.

• Circular and distorted.

• Bell-shaped and symmetric.

• Square and flat.