SCO 2550

Two events A and B are mutually exclusive and the two events make up the entire sample space, what is the probability that either A occurs or B occurs or both?

1.0

What value of z corresponds to a 95% confidence interval?

1.96

According to the text, the shape of the sampling distribution of the statistic p hat is

Approximately normal if the sample size n is 'large'

The characteristics of the normal probability distribution include all of the following with the exception of?

Each trials results in a success or a failure

Which of the following is the correct interpretation of a 95% confidence interval for the population mean?

If we sampled from the population all possible times for a specified sample size and calculated all possible 95% confidence intervals, then 95% of those confidence intervals will contain the population mean

The quantity that is added to and subtracted from a point estimate of a population parameter to obtain a confidence interval for the parameter is defined as the

Margin of Error

If events A and B are mutually exclusive, what is the P(A intersect B)?

zero

A sample statistic is an unbiased point estimate of a population parameter if

The mean of all possible values of the sample statistic equals the corresponding population parameter

Which of the following best describes the definition of the sampling distribution of the sample mean?

The probability distribution of the population of all sample means obtained from samples of a particular size n

Which of the following best describes the definition of the sampling distribution of the sample proportion?

The probability distribution of the population of all sample proportions obtained from samples of a particular size n

Which of the following best describes the standard deviation of the sampling distribution of the statistic p hat?

The square root of the result when you take the (population proportion p multiplied by (1 minus p)) divided by the sample size n

Which of the following best describes the definition of the minimum variance property?

The unbiased point estimator of a population parameter having a variance that is smaller than the variance of any other unbiased point estimator

Suppose you do not know the population standard deviation but you do know that the shape of the population is normal. How would you go about calculating a confidence interval for the population mean?

Use the point estimator plus and minus t times the standard error of the mean

Which of the following is the correct interpretation of a 95% confidence interval for the population proportion?

We are 95% confident that the population proportion is within the interval from ____ to ____

When would you use the t-distribution to calculate a confidence interval for the population mean?

When estimating the population mean with an unknown sigma but a population that is normally distributed

Purchase intentions (Xi) of consumers are measured by a survey where consumer responses are 1) not purchase, 2) likely to purchase, 3) highly likely to purchase. Which of the following best describes the random variable Xi?

Xi is a discrete random variable

Which of the following statements are true regarding the Multiplicative Rule of Probability ? 1. P(A intersect B) = P(A)P(B|A) 2. P(A intersect B) = P(B)P(A|B)

both statements are true

`What is the value of p that yields the largest possible standard error of the sampling distribution of the statistic p hat?

.50

Opening up the monthly cell phone bill can be alarming due to the uncertainty of the bill. Suppose the amount of minutes used per month is distributed normally with a mean of 700 minutes and a standard deviation of 120 minutes. What is the probability that more than 940 minutes were used?

0.0228

Suppose the commute times for students attending night classes at the U are normally distributed with a mean of 25 minutes and a standard deviation of 5 minutes. What range of commute times will include approximately 95% of the times?

15 to 35 minutes

The likelihood of repeat purchases by the same customer can dramatically improve overall profitability for an auto dealership. Suppose purchase intentions follow a binomial random variable with a probability of repeat purchases (a success) of 0.35. If a random sample of 100 customers is selected, what is the mean number of customers who are expected to purchase again?

35

Suppose the commute times for students attending night classes at the U are normally distributed with a mean of 25 minutes and a standard deviation of 5 minutes. What percent of commute times are longer than 25 minutes?

50%

Suppose the amount of coffee consumed per year by a college student is normally distributed with a mean of 15,000 ounces and a standard deviation of 3,000 ounces. What percent of students will consume between 9,000 and 21,000 ounces of coffee per year?

95.44%

Which of the following best describes the proportion of observations within plus and minus two standard deviations of the mean for a normal distribution?

95.44%

Suppose the commute times for students attending night classes at the U are normally distributed with a mean of 25 minutes and a standard deviation of 5 minutes. Approximately what percent of commute times are between 10 minutes and 40 minutes?

99.7%

Suppose the commute times for students attending night classes at the U are normally distributed with a mean of 25 minutes and a standard deviation of 5 minutes. What percent of commute times are between 10 minutes and 40 minutes?

99.73%

How would you go about calculating the expected value of the discrete random variable shown below: Xi P(Xi) 10 0.15 30 0.30 50 0.20 70 0.35

Multiply Xi times P(Xi) and add them up. Do not divide the sum by anything.

Which of the following statements are true? 1) The value of the random variable (xi) cannot be negative 2) The value of the probability of a random variable P(xi) cannot be negative

Only statement 2 is true; The value of the probability of a random variable P(xi) cannot be negative

You and your friend have graduated and just entered the job market. Let event A represent the event that you receive a job offer. Let event B represent the event that your friend receives a job offer. Which of the following represents the event that either A or B or both receive job offers?

P(A U B)

You and your friend have just graduated and entered the job market. Let event A represent the event that you receive a job offer. Let event B represent the event that your friend receives a job offer. Which of the following represents the event that both you and your friend receive job offers?

P(A intersect B)

Which of the following statements is true about the multiplicative rule of probability?

P(A intersect B) = P(B)P(A|B)

Which of the following best describes the Central Limit Theorem? The Central Limit Theorem describes the

Shape of the sampling distribution of the statistic x bar

Suppose a distribution is symmetric, unimodal and extends from negative infinity to positive infinity. Which of the following fits best?

The distribution is a normal probability distribution

The probability that a confidence interval for a population parameter will contain the population parameter is defined as the

confidence coefficient

Suppose two 99% confidence intervals are calculated. One interval is based on a sample of size 30 and the other on a sample of size 60. Which of the following statements is correct regarding the confidence interval based on the smaller sample of size 30? The confidence interval based on the sample of size 30

is wider

Which of the following statements best describes the Additive Rules of Probability?

it determines the probability of either A or B or both occuring

Out of the class of all unbiased point estimators for a population parameter, the preferred point estimator is the one that has

minimum variance

Which of the following best fits with the probabilities for events A, B, C that are independent?

multiply the individual event probabilities to calculate the probability of the intersection between events A, B, C

All possible samples of size 30 are drawn from a population that is a uniform height distribution with a known standard deviation. Which of the following best describes the shape of the distribution of all possible sample means?

normal distribution