Q: In a data set of 20 values, what is the percentile rank of the 5th value when the values are ordered from smallest to largest?

$$\frac{5}{20} \times 100 = 25\%$$

Q: A box contains 3 red, 2 blue, and 5 green balls. If two balls are drawn without replacement, what is the probability that both are green?

$$\frac{5}{10} \times \frac{4}{9} = \frac{20}{90} = \frac{2}{9}$$

Question 1

A medical researcher wants to study the effect of a new drug on blood pressure. She randomly assigns 100 patients to either receive the drug or a placebo and measures their blood pressure after 6 weeks. What type of study is this?

Accepted Answer

Experiment

Question 2

Which of the following best describes a parameter?

Accepted Answer

A value that describes a characteristic of a population

Question 3

A researcher uses a random number generator to select 50 students from a university's enrollment list. Which sampling method is being used?

Accepted Answer

Simple random sampling

Question 4

Given the following frequency distribution, what is the cumulative frequency for the third class?

Class: 1-10 (5), 11-20 (8), 21-30 (12), 31-40 (7)

Accepted Answer

25

Question 5

Which of the following is NOT a deceptive graph technique?

Accepted Answer

Using proportional scaling for all axes

Question 6

Given the data set: 2, 4, 4, 6, 8, what is the mode?

Accepted Answer

$$4$$

Question 7

A set of exam scores has a mean of $$70$$ and a standard deviation of $$10. $$According to the range rule of thumb, what is the minimum 'usual' value?

Accepted Answer

$$50$$

Question 8

If a data set is approximately normal, what percentage of values fall within two standard deviations of the mean according to the empirical rule?

Accepted Answer

$$95\%$$

Question 9

A student scored $$85 on a $$test where the mean was $$80$$ and the standard deviation was $$5. $$What is the student's z-score?

Accepted Answer

$$z = 1$$

Question 10

In a data set of 20 values, what is the percentile rank of the 5th value when the values are ordered from smallest to largest?

Accepted Answer

$$\frac{5}{20} 	imes 100 = 25\%$$

Question 11

Which of the following statements about probabilities is correct?

Accepted Answer

Probabilities are values between 0 and 1, inclusive

Question 12

If $$P(A) = 0.3$$ and $$P(B) = 0.5$$, and $$A$$ and $$B$$ are not mutually exclusive, $$P(A \cap B) = 0.1. $$What is $$P(A \cup B)$$?

Accepted Answer

$$0.9$$

Question 13

If the probability of rain tomorrow is $$0.2$$, what is the probability that it will NOT rain?

Accepted Answer

$$0.8$$

Question 14

A box contains 3 red, 2 blue, and 5 green balls. If two balls are drawn without replacement, what is the probability that both are green?

Accepted Answer

$$\frac{5}{10} 	imes \frac{4}{9} = \frac{20}{90} = \frac{2}{9}$$

Question 15

How many ways can 4 students be seated in a row?

Accepted Answer

$$4! = 24$$

Question 16

A committee of 3 is to be chosen from 10 people. How many different committees are possible?

Accepted Answer

$$\binom{10}{3} = 120$$

Question 17

Which sampling method involves dividing the population into groups and randomly selecting entire groups?

Accepted Answer

Cluster sampling

Question 18

A stemplot is most useful for which type of data?

Accepted Answer

Quantitative data

Question 19

If a boxplot shows a long whisker on the right side, what does this indicate about the data?

Accepted Answer

The data is right-skewed

Question 20

A hospital records the blood types of 100 patients. Which measure of center is most appropriate for this data?

Accepted Answer

Mode

Elementary Statistics: Chapters 1-4 Study Guide

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