Bài kiểm tra đánh giá: Essential of Business Statistics

Which measurement scale has a meaningful absolute zero and allows statements such as 'twice as much'?

A marketing analyst wants to examine the relationship between advertising expenditure (in dollars) and monthly sales (in dollars) for 30 stores. Which graph is most appropriate?

For a data set that is skewed to the right, which of the following is generally true?

Which numerical descriptive measure is most affected by extreme outliers?

If P(A) = 0.4, P(B) = 0.5, and P(A∩B) = 0.2, then P(A∪B) equals:

Which of the following is a discrete random variable?

Which set of probabilities is NOT a valid discrete probability distribution?

Let X have probability distribution: P(X=0)=0.2, P(X=1)=0.5, P(X=2)=0.3. The mean E(X) is:

Which of the following is NOT a condition of a binomial experiment?

For a Poisson random variable with mean λ = 2.5, the variance is:

The standard normal distribution has:

According to the Central Limit Theorem, for a sufficiently large random sample of size n, the sampling distribution of the sample mean x̄ is approximately normal with:

Which formula is used to construct a confidence interval for the population mean when the population standard deviation σ is known?

In a hypothesis test, if the p-value is 0.03 and the significance level α is 0.05, the correct conclusion is:

In hypothesis testing, rejecting a true null hypothesis is called:

In simple linear regression, if R² = 0.81, the correct interpretation is:

Complete the two requirements of a valid discrete probability distribution: for every value of x, 0 ≤ P(x) ≤ ____, and the sum of all probabilities ΣP(x) = ____.

A company recorded the daily number of customer complaints X for 100 days: X=0,1,2,3 with probabilities 0.1, 0.4, 0.3, and 0.2. Compute the mean and standard deviation of X. Show your work.

Explain the difference between a discrete random variable and a continuous random variable. Give two examples of each, and explain why the binomial distribution and the normal distribution are commonly used for these two types.

A store manager believes the average waiting time is less than 5 minutes. Describe how to conduct a hypothesis test of this claim. Include the null and alternative hypotheses, the meaning of the significance level α and the p-value, and the decision rule. Also explain what Type I and Type II errors would mean in this waiting-time context.