Q: A nurse measures the systolic blood pressure of 30 patients aged 25-40 years. The relative frequency histogram shows that 30% of patients have a systolic blood pressure between 110 and 130 mm Hg. What percentage of patients is this?

$$ 0.3 \times 30 = 9 $$ patients

Question 1

A researcher wants to estimate the average number of hours college students sleep per night. She surveys 200 randomly selected students from her university and finds a mean of 6.8 hours. Which of the following best describes the value 6.8 hours?

Accepted Answer

It is a statistic because it describes a sample.

Question 2

Which of the following is an example of a discrete variable?

Accepted Answer

The number of cars passing through an intersection in an hour.

Question 3

A study records the blood types (A, B, AB, O) of 500 patients at a hospital. What is the level of measurement for this data?

Accepted Answer

Nominal

Question 4

A teacher assigns letter grades (A, B, C, D, F) to students based on their performance. What is the level of measurement for the grades?

Accepted Answer

Ordinal

Question 5

A scientist measures the pH levels of different lakes. The pH scale is an example of which level of measurement?

Accepted Answer

Interval

Question 6

A company wants to know if a new training program increases employee productivity. They randomly assign half of their employees to the new program and the other half to the old program, then compare results. What type of study is this?

Accepted Answer

Experiment

Question 7

A researcher collects data on the number of books read by students in a semester. The data are: 2, 5, 3, 4, 6, 2, 3, 5, 4, 3. What is the mean number of books read?

Accepted Answer

$$ \frac{37}{10} = 3.7 $$

Question 8

A hospital administrator wants to estimate the average length of stay for all patients. She randomly selects every 10th patient admitted during a month. What type of sampling is this?

Accepted Answer

Systematic sampling

Question 9

Which of the following is an example of a continuous variable?

Accepted Answer

The weight of apples in a grocery store.

Question 10

A survey asks respondents to rate their satisfaction on a scale from 1 (very dissatisfied) to 5 (very satisfied). What is the level of measurement for this data?

Accepted Answer

Ordinal

Question 11

A biologist records the lengths (in centimeters) of fish caught in a lake. Which level of measurement is appropriate for this data?

Accepted Answer

Ratio

Question 12

A marketing firm wants to study the preferences of smartphone users in the U.S. They divide the country into regions and randomly select several regions, then survey all users in those regions. What type of sampling is this?

Accepted Answer

Cluster sampling

Question 13

A researcher wants to compare the average test scores of students in different majors. She randomly selects 50 students from each major. What type of sampling is this?

Accepted Answer

Stratified sampling

Question 14

A study collects data on the number of hours people watch TV per week by asking a random sample of adults. What type of study is this?

Accepted Answer

Observational study

Question 15

A frequency distribution table for test scores is given below:

Scores: 60-69, 70-79, 80-89, 90-99
Frequency: 5, 6, 15, 6

What is the class width?

Accepted Answer

$$ 10 $$

Question 16

A nurse measures the systolic blood pressure of 30 patients aged 25-40 years. The relative frequency histogram shows that 30% of patients have a systolic blood pressure between 110 and 130 mm Hg. What percentage of patients is this?

Accepted Answer

$$ 0.3 	imes 30 = 9 $$ patients

Question 17

A cumulative frequency distribution is constructed from the following frequency distribution:

Class: 0-9, 10-19, 20-29, 30-39
Frequency: 4, 6, 10, 5

What is the cumulative frequency for the class 20-29?

Accepted Answer

$$ 4 + 6 + 10 = 20 $$

Question 18

A quality control analyst inspects the first 100 items produced in a day. What type of sampling is this?

Accepted Answer

Convenience sampling

Question 19

A town polls 10,000 of its citizens this month to obtain current employment data. What type of observational study is this?

Accepted Answer

Cross-sectional

Question 20

A researcher plans to obtain data by examining the financial transactions of victims who perished in a bombing. What type of observational study is this?

Accepted Answer

Retrospective

Fundamentals of Statistics: Concepts, Data Types, Sampling, and Data Representation

Guida di studio - Domande di pratica

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