Exam 2 Review

Question 1

6. If a certain number of examinations are selected at random and their mean is calculated, what is the expected average score?

Answer 1

Avg is = to given mean

Question 2

7. How to find standard deviation of the average score?

Answer 2

Question 3

8. How to know if the distribution of scores/data is approximately or exactly normal?

Answer 3

Approximately: Around the mean
Exactly: Equal to the mean

Question 4

What are parameters?

Answer 4

Describe the population

Question 5

What are statistics?

Answer 5

Describes the sample

Question 6

What is a subset of a population?

Answer 6

Describes the same group of individuals

Question 7

What is point estimate?

Answer 7

The sample mean is called a point estimate of the population mean μ.

Question 8

What is the confidence level?

Answer 8

indicates the probability, with which the estimation of the location of a statistical parameter (e.g. an arithmetic mean) in a sample survey is also true for the population.

Question 9

What is the margin of error?

Answer 9

a statistic expressing the amount of random sampling error in a survey’s results. The larger the margin of error, the less confidence one should have that the data’s reported results are close to the ‘true’ figures

Question 10

What is an interval estimate?

Answer 10

estimated range of values for a statistic

Question 11

What are the following confidence intervals?
90%
95%
98%
99%

Answer 11

90% -> 1.645
95% -> 1.96
98% -> 2.33
99% ->2.57

Question 12

What’s the critical z-value for a 99% confidence interval?

Answer 12

2.575 or 2.58

Question 13

13. Decreasing the sample size, while holding the confidence level the same, will do what to the length of your confidence interval?

Answer 13

Makes it bigger

Question 14

14. Decreasing the confidence level, while holding the sample size the same, will do what to the length of your confidence interval?

Answer 14

Makes it smaller

Question 15

You take a random sample from some population and form a 96% confidence interval for the population mean, μ. Which quantity is guaranteed to be in the interval you form?

Answer 15

• x-bar (sample mean)

Question 16

When asked for the sample standard deviation of the sample mean, what equation should you use?

Answer 16

Question 17

When asked for the sample standard deviation of the sample mean, what equation should you use?

Answer 17

Question 18

What is the equation for finding the confidence interval?

Answer 18

Note that for Z just use memorized confidence intervals.

Question 19

How to find the margin of error of a confidence interval?

Answer 19

(sample standev times confidence interval)

Question 20

How to find a specific n value given pieces of standev of sample mean formula?

Answer 20

E: Margin of error
Z: Confidence interval value

Question 21

How to find the standard error of the sample mean of a certain given n value.

Answer 21

Question 22

How to find the probability of something with normal distribution given mean and standev?

Answer 22

Z = (value-mean) / standev