Log inSign up for FREE
Library

HW3: Inferences

Last updated almost 4 years ago
17 questions
Note from the author:
Mean and Standard Deviation Calculator.

\sigma = standard deviation (SD)
N = size of the data (number of values)
\mu = mean
​x_{i} = data value​
z = z-score

\mu = \frac{\sum x_{i}}{N}​​​​​​
z = \frac{x-\mu}{\sigma}​​​
margin of error (MOE) = \frac{2\sigma}{\sqrt{N}}
Mean and Standard Deviation Calculator.

\sigma = standard deviation (SD)
N = size of the data (number of values)
\mu = mean
​x_{i} = data value​
z = z-score

\mu = \frac{\sum x_{i}}{N}​​​​​​
z = \frac{x-\mu}{\sigma}​​​
margin of error (MOE) = \frac{2\sigma}{\sqrt{N}}
1

Faith asks her math teacher if she did well on the last test. Her teacher replies saying that Faith's z-score was 1.5.

Did Faith do well on the last test? How do you know?

1

On a homework assignment, Blake calculates a z-score of -6.2. Dwayne tells Blake that a z-score of -6.2 is not reasonable. Is Dwayne right? Why or why not?

1

A data value has a z-score of 1.56.

The data value is greater than what percent of the population values?

Enter your answer as a percentage (no % sign) rounded to two decimal places.

1

A data value has a z-score of 0.23.

The data value is less than what percent of the population values?

Enter your answer as a percentage (no %) rounded to two decimal places.

1

A sample data set has a mean of 82 and a standard deviation of 4.6.

A data value of 87 is greater than what percent of the population values?

Enter your answer as a percentage (no %) rounded to two decimal places.

1

A sample data set has a mean of 100 and a standard deviation of 10.

A data value of 75 is less than what percent of the population values?

Enter your answer as a percentage (no %) rounded to two decimal places.

1

A sample data set has a mean of 100 and a standard deviation of 10.

A data value of 80 is greater than what percent of the population values?

Enter your answer as a percentage (no %) rounded to two decimal places.

1

As sample size increases, the margin of error ___________________.

1

A data set has a size of 25, a mean of 85, and a standard deviation of 2.

What is the range of reasonable values for the true mean, x?

1

A data set has a size of 500, a mean of 1000, and a standard deviation of 15.

What is the range of reasonable values for the true mean, x?

1

A data set has a mean of 3 and a standard deviation of 4.

If the margin of error is \pm 0.25, what was the sample size?

1

Review:
What is something that sample surveys and experiments have in common, but observational studies do not?

1

Review:
Categorize the descriptions.

  • A researcher notes which college students bring coffee to school and how frequently. They obtain the records of the students' grades.
  • A researcher collects data without interacting with the people/thing being studied
  • A researcher asks each student in a college class whether they drink coffee in the morning, and whether they think it improves their grades.
  • A researcher creates random groups, applies a treatment to each, and compares the results.
  • A researcher collects data by asking a sample group some questions and recording the answers
  • A researcher gives half the college class coffee for a month, then compares the grades of those who were given coffee and those who weren't.
  • Observational Studies
  • Sample Surveys
  • Experiments
1

Review:
Gabriela wants to know students favorite subject in school. She plans to ask a sample of students "What is your favorite subject in school?".

Which of the following sampling methods prevent significant bias?

Review
Use the data from the table below for the following questions.


1

Calculate the mean of the data.

1

Calculate the standard deviation of the data, to the nearest tenth.

1

What is the z-score of a data value of 13?

Round your answer to the nearest hundredth.