Question 1

Which of the following best describes a parameter in statistics?

Accepted Answer

A numerical characteristic of an entire population.

Question 2

A pharmaceutical company wants to test a new drug. They randomly assign patients to receive either the drug or a placebo and measure their recovery rates. What type of study is this?

Accepted Answer

Experiment

Question 3

Which sampling method is most likely to introduce bias due to self-selection?

Accepted Answer

Voluntary response sampling

Question 4

Given the following data set: 2, 4, 4, 6, 8. What is the sample mean?

Accepted Answer

$$\frac{2+4+4+6+8}{5} = 4.8$$

Question 5

Which of the following is NOT a characteristic of a normal distribution?

Accepted Answer

Skewed right

Question 6

If a data set is perfectly symmetric, which of the following statements is true?

Accepted Answer

The mean equals the median.

Question 7

A researcher collects the blood types of 1000 people. What type of variable is blood type?

Accepted Answer

Categorical (qualitative)

Question 8

Which formula correctly calculates the sample variance for a data set $$x_1$$, $$x_2$$, ..., x_n$$?

Accepted Answer

$$s^2$$ = \frac{\sum (x_i - \bar{x}$$)^2$$}{n-1}$$

Question 9

A distribution is described as 'positively skewed.' Which of the following is most likely true?

Accepted Answer

The mean is greater than the median.

Question 10

If $$P(A) = 0.4$$ and $$P(B) = 0.5$$ and $$A$$ and $$B$$ are independent, what is $$P(A \cap B)$$?

Accepted Answer

$$0.4 	imes 0.5 = 0.2$$

Question 11

A deck of cards has 52 cards. What is the probability of drawing an Ace or a King in one draw?

Accepted Answer

$$\frac{8}{52}$$

Question 12

Which of the following best describes a lurking variable?

Accepted Answer

A variable that is not measured but affects the response variable.

Question 13

What is the interquartile range (IQR) for the data set: 2, 4, 6, 8, 10?

Accepted Answer

$$IQR = Q_3$ - Q_1$ = 8 - 4 = 4$$

Question 14

If the probability of event $$A is$$ $$0.7$$, what is the probability of its complement?

Accepted Answer

$$0.3$$

Question 15

A researcher wants to select a sample that represents all age groups in a city. Which sampling method should they use?

Accepted Answer

Stratified random sampling

Question 16

Which formula gives the number of ways to choose 3 students from a group of 10, where order does NOT matter?

Accepted Answer

$$C_{10}^3 = \frac{10!}{3!7!}$$

Question 17

Which of the following is true about the empirical rule for a normal distribution?

Accepted Answer

About 68% of observations lie within 1 standard deviation of the mean.

Question 18

A z-score is calculated as:

Accepted Answer

$$z = \frac{x_i - \bar{x}}{s}$$

Question 19

Which of the following best describes confounding in an observational study?

Accepted Answer

It is when two variables' effects cannot be distinguished on the response variable.

Question 20

If a linear transformation is applied to a variable $$x$$ such that $$x^* = a + bx$$, what is the mean of the transformed variable?

Accepted Answer

$$\bar{x}^* = a + b\bar{x}$$

STAT 2040 Statistics I: Structured Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드