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QMB 3200 MIDTERM UCF PRACTICE
EXAM 2 QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2025
- A manager wants to estimate the average sales per month for all stores in a region. Which of the following best describes the population? A) The sample of stores the manager selects B) The average monthly sales of one store C) All stores in the region D) The standard deviation of sales of the sample Answer: C The population is the entire group the manager wants to learn about — in this case, all stores in the region.
- Which of the following is a point estimator for the population mean? A) Sample mean B) Population mean C) Population standard deviation D) Sample variance Answer: A A point estimator provides a single value as an estimate of a population parameter. The sample mean is the point estimator of the population mean.
- The sum of the deviations of each value from the mean for a dataset will always be: A) Equal to 1 B) Greater than zero C) Less than zero D) Equal to zero Answer: D By definition, the mean balances the data. So the sum of deviations from the mean must be zero.
- If the probability of an event is 0.20, what are the odds in favor of the event? A) 1 to 4
Answer: C The mean is pulled in the direction of extreme values, so it is most affected by outliers.
- If a random variable follows a normal distribution with mean 100 and standard deviation 10, what is the probability of observing a value greater than 120? A) 0. B) 0. C) 0. D) 0. Answer: C Z = (120 - 100)/10 = 2. P(Z > 2) = 0.0228. Be careful! But the correct value is 0.0228, which is not an option here, so the closest option is 0.0228 which should have been included. (Correction: The correct answer should be D. P(Z > 2) = 0.0228.)
- If the standard deviation of a population is 15, what is the standard error of the mean for a sample size of 25? A) 15 B) 3
C) 5
D) 0.
Answer: B Standard error = σ / √n = 15 / √25 = 15/5 = 3.
- In a confidence interval for the population mean, increasing the sample size will: A) Increase the margin of error B) Decrease the margin of error C) Not affect the margin of error D) Eliminate sampling error completely Answer: B Larger sample sizes reduce the standard error, which reduces the margin of error.
- What does the level of confidence represent in a confidence interval? A) The probability that the sample mean equals the population mean B) The probability that the population parameter is within the sample statistic C) The proportion of intervals that would contain the parameter if you
Answer: C Weight can take on an infinite number of values within a range, so it is continuous.
- In hypothesis testing, what is a Type I error? A) Failing to reject a true null hypothesis B) Rejecting a true null hypothesis C) Failing to reject a false null hypothesis D) Rejecting a false alternative hypothesis Answer: B A Type I error occurs when you reject the null hypothesis when it is actually true.
- Which Excel function would you use to find the probability of a normal random variable being less than a certain value? A) =NORM.S.DIST(z, TRUE) B) =NORM.INV(probability, mean, standard_dev) C) =NORM.DIST(x, mean, standard_dev, TRUE) D) =NORM.S.INV(probability) Answer: C =NORM.DIST(x, mean, standard_dev, TRUE) gives the cumulative probability for the normal distribution.
- The mean of the sampling distribution of the sample mean is equal to: A) The population standard deviation B) The sample mean C) The population mean D) Zero Answer: C The mean of the sampling distribution of the sample mean is equal to the population mean.
- Which measure of dispersion is defined as the average of the squared deviations from the mean? A) Range B) Standard deviation C) Variance D) Interquartile range Answer: C Variance is defined as the mean of the squared deviations from the mean.
- The empirical rule states that for a normal distribution, about 95% of data falls within how many standard deviations from the
C) Probability D) Mean Answer: C The total area under the normal curve equals 1, representing the total probability.
- Which of the following is an example of non-sampling error? A) Using a random sample B) Choosing a small sample size C) Data entry mistakes D) Using a systematic sample Answer: C Non-sampling errors include human errors like data entry mistakes.
- The probability of two independent events both occurring is found by: A) Adding the probabilities B) Multiplying the probabilities C) Dividing the probabilities D) Subtracting the probabilities Answer: B For independent events, P(A and B) = P(A) × P(B).
- What is the mode of the dataset: 4, 7, 4, 9, 11, 4, 7? A) 4 B) 7 C) 9 D) 11 Answer: A The mode is the most frequently occurring value, which is 4.
- The symbol σ² represents: A) Population variance B) Population standard deviation C) Sample variance D) Sample standard deviation Answer: A σ² denotes the population variance.
- The larger the standard deviation, the: A) Closer the data points are to the mean B) Smaller the range C) More spread out the data is D) More normal the distribution
B) 1.
C) 0.
D) 1.
Answer: C Probabilities must be between 0 and 1 inclusive.
- If the null hypothesis is that μ = 50 and the sample mean is 60, this suggests: A) The null hypothesis is true B) The population mean must be 60 C) The sample provides evidence against H₀ D) The sample mean must be incorrect Answer: C A large difference between the sample mean and hypothesized mean provides evidence to reject H₀.
- What happens to the width of a confidence interval if the confidence level increases from 90% to 95%? A) It decreases B) It stays the same C) It increases D) It becomes zero
Answer: C Higher confidence levels mean wider intervals because you need to be more certain.
- What Excel function can calculate the standard deviation of a sample? A) =AVERAGE B) =VAR.P C) =STDEV.S D) =STDEV.P Answer: C =STDEV.S calculates the sample standard deviation.
- The shape of the sampling distribution of the sample mean is approximately normal when: A) The sample size is large B) The population is uniform C) The mean is zero D) The sample variance is zero Answer: A According to the Central Limit Theorem, the sampling distribution approaches normality as n increases.
C) Categorical D) Nominal Answer: B Continuous variables can take any value within a range.
- If two events are mutually exclusive, then their intersection is: A) Equal to their union B) Zero C) One D) Equal to the sum of probabilities Answer: B Mutually exclusive events cannot occur together, so their intersection is zero.
- Which sampling method divides the population into subgroups and samples each group? A) Cluster B) Systematic C) Simple random D) Stratified Answer: D Stratified sampling divides the population into strata and samples each one.
- The standard error will decrease if: A) The population variance increases B) The sample size increases C) The sample mean increases D) The confidence level increases Answer: B Increasing the sample size reduces the standard error.
- Which of the following is an example of parameter? A) Sample mean B) Population mean C) Sample proportion D) Sample standard deviation Answer: B A parameter describes a characteristic of the population.
- If you flip a coin three times, what is the probability of getting exactly two heads? A) 0. B) 0. C) 0. D) 0.
B) Zero or positive C) Greater than the mean D) Smaller than variance Answer: B Standard deviation cannot be negative.
- Which level of measurement classifies data into categories with no order? A) Interval B) Ratio C) Ordinal D) Nominal Answer: D Nominal data can be named but not ordered.
- A Z-score tells you: A) The mode of the data B) The range of the data C) How many standard deviations a value is from the mean D) The standard error
Answer: C A Z-score standardizes a value in relation to the mean and standard deviation.
- If you increase the sample size, what happens to the variance of the sampling distribution? A) It stays the same B) It increases C) It decreases D) It becomes infinite Answer: C Larger samples reduce variability in the sampling distribution.
- Which is an example of a subjective probability? A) A coin toss B) Probability estimated from surveys C) A weather forecast based on intuition D) Probability from historical frequencies Answer: C Subjective probability is based on judgment or intuition.
