Question

select the correct answer.
which statement is true?
a. a sample statistic can never be equal to the population parameter.

b. point estimates are defined for both samples and populations.

c. to calculate a sample proportion, we need to know the population size.

d. to calculate a point estimate, we need to know the sample size.

Explanation:

Step 1: Analyze Option A

A sample statistic can sometimes be equal to the population parameter (e.g., if the sample is the entire population or by chance), so A is false.

Step 2: Analyze Option B

Point estimates are used for samples (to estimate population parameters), not for populations (since population parameters are known, not estimated). So B is false.

Step 3: Analyze Option C

To calculate a sample proportion, we use the number of successes in the sample and the sample size, not the population size. So C is false.

Step 4: Analyze Option D

A point estimate (e.g., sample mean, sample proportion) requires knowing the sample size (e.g., sample proportion is $\frac{\text{number of successes in sample}}{\text{sample size}}$). So D is true.

Answer:

D. To calculate a point estimate, we need to know the sample size.