Populations, censuses and samples Quiz

1. An examiner chooses 30 scripts from the list of all 600 scripts. The list of 600 scripts is

• A. the sample
• B. the population
• C. the sampling frame
• D. a statistic

2. Which is the best reason for using a sample rather than a census to test the lifetime of light bulbs?

• A. Testing a bulb's lifetime uses it up
• B. Samples are always more accurate
• C. A census gives biased results
• D. Bulbs cannot be numbered

3. A population has unknown mean $\mu$ and unknown variance $\sigma^2$. Which is a statistic for a sample $X_1,\dots,X_4$?

• A. $\frac{X_1-\mu}{\sigma}$
• B. $\frac{X_1+X_2+X_3+X_4}{4}$
• C. $\sigma+X_2$
• D. $\mu-X_4$

4. A population is the numbers 1, 2, 3 and samples of size 2 are taken with replacement. What is P(the smaller number is 3)?

• A. $\frac13$
• B. $\frac29$
• C. $\frac59$
• D. $\frac19$

5. What does the sampling distribution of a sample mean describe?

• A. The spread of values in the population
• B. The values in one sample
• C. How the sample mean varies from sample to sample
• D. The size of the sample