Deck 7: Estimating Parameters and Determining Sample Sizes

Question 1

The margin of error ________ ________ (increases or decreases)with an increase in confidence level.

A) increases; increases
B) increases; decreases
C) decreases; increases
D) decreases; decreases

Answer 1

C

Question 2

Answer 2

C

Question 3

Find the critical value corresponding to a sample size of 19 and a confidence level o? 99 percent.

A) 37.156
B) 6.265
C) 34.805
D) 7.015

Answer 3

A

Question 4

Assume that a sample is used to estimate a population proportion p. Find the margin of error E that corresponds to the given statistics and confidence level. Round the margin of error to four
Decimal places.
98% confidence; the sample size is 800, of which 40% are successes

A) 0.0355
B) 0.0339
C) 0.0404
D) 0.0446

Question 5

Question 6

Question 7

Question 8

Of 380 randomly selected medical students, 21 said that they planned to work in a rural community. Find a 95% confidence interval for the true proportion of all medical students
Who plan to work in a rural community.

Question 9

Fifty people are selected randomly from a certain population and it is found that 12 people in the sample are over six feet tall. What is the best point estimate of the proportion of people in
The population who are over 6 feet tall?

A) 0.76
B) 0.24
C) 0.50
D) 0.18

Question 10

Question 11

If the computed minimum sample size n needed for a particular margin of error is not a whole number, round the value of n _______ (up or down)to the next ________ (smaller or larger)
Whole number.

A) up; smaller
B) up; larger
C) down; smaller
D) down; larger

Question 12

Find the critical value that corresponds to a 91% confidence level.

A) 1.34
B) 1.645
C) 1.70
D) 1.75

Question 13

Assume that a sample is used to estimate a population proportion p. Find the margin of error E that corresponds to the given statistics and confidence level.
95% confidence; n = 2388, x = 1672

A) 0.0248
B) 0.0184
C) 0.0156
D) 0.0206

Question 14

Use the given degree of confidence and sample data to construct a confidence interval for the population proportion p.

Question 15

Find the value of that corresponds to a confidence level of 89.48%.

A) 1.25
B) 1.62
C) 0.0526
D) −1.62

Question 16

Use the given data to find the minimum sample size required to estimate the population proportion.
Margin of error: 0.028; confidence level: 99%; p and q unknown

A) 1116
B) 2223
C) 1939
D) 2115

Question 17

Question 18

Question 19

Identify the distribution that applies to the following situation? In constructing a confidence interval of you have 50 sample values and they appear to be
From a population with a skewed distribution.

A) Student t distribution
B) Normal distribution
C) Chi-square distribution
D) None of the three distributions is appropriate.

Question 20

Question 21

Question 22

Question 23

Question 24

Question 25

Question 26

4)Find the critical value corresponding to a sample size of 19 and a confidence level of 99 percent.

A) 37.156
B) 6.265
C) 34.805
D) 7.015

Question 27

Fill in the blank: The critical value that corresponds to a _________% confidence level is 2.33.

A) 88
B) 90
C) 98
D) 99

Question 28

Question 29

Question 30

To be able to say with 95% confidence that the standard deviation of a data set is within 10% of the population's standard deviation, the number of observations within the data set must be
Greater than or equal to what quantity?

A) 805
B) 192
C) 335
D) 250

Question 31

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Question 36

Question 37

Question 38

Question 39

Identify the distribution that applies to the following situation: In constructing a confidence interval of , you have 50 sample values and they appear to be
From a population with a skewed distribution. The population standard deviation is not
Known. ______________

A) Student t distribution
B) Normal distribution
C) Chi-square distribution
D) None of the three distributions is appropriate.

Question 40

You want to be 95% confident that the sample variance is within 40% of the population variance. Find the appropriate minimum sample size.

A) 57
B) 224
C) 14
D) 11

Question 41

The following is a 95% confidence interval of the proportion of female medical school
students: 0.449 < p < 0.511, based on data from the American Medical Association. What is
the point estimate of the proportion of females in the population of medical school students?
Write a brief statement that correctly interprets the confidence interval given.

Question 42

In a Gallup poll, 1011 adults were asked if they consume alcoholic beverages and 64% of
them said that they did. Construct a 90% confidence interval estimate of the proportion of all
adults who consume alcoholic beverages. Can we safely conclude that the majority of adults
consume alcoholic beverages?

Question 43

Describe the process for finding the confidence interval for a population proportion.

Question 44

Identify the correct distribution (z, t, or neither)for each of the following.

Question 45

In a Gallup poll of 557 randomly selected adults, 284 said that they were underpaid. Identify
the best point estimate of the percentage of adults who say they are underpaid. Construct a
95% confidence interval estimate of the percentage of adults who say that that they are
underpaid. Can we safely conclude that the majority of adults say that they are underpaid?

Question 46

Interpret the following 95% confidence interval for mean weekly salaries of shift managers
at Guiseppe's Pizza and Pasta.
325.80 < < 472.30

Question 47

Six human skulls from around 4000 B.C. were measured, and the lengths have a mean of
94.2 mm and a standard deviation of 4.9 mm. If you want to construct a 95% confidence
interval estimate of the mean length of skulls, what requirements must be satisfied?

Question 48

Based on a simple random sample of students from her school, Sally obtained a point
estimate of the mean weight of students at her school. What additional information would
be provided by a confidence interval estimate of the mean weight?

Question 49

Draw a diagram of the chi-square distribution. Discuss its shape and values.

Question 50

In a Gallup poll, 1011 adults were asked if they consume alcoholic beverages and 64% of
them said that they did. Construct a 90% confidence interval estimate of the proportion of all
adults who consume alcoholic beverages. Can we safely conclude that the majority of adults
consume alcoholic beverages?

Question 51

How do you determine whether to use the z or t distribution in computing the margin of error,

Question 52

Question 53

You want to estimate σ for the population of waiting times at McDonald's drive-up windows,
and you want to be 95% confident that the sample standard deviation is with 20% of . Find
the minimum sample size. Is this sample size practical?

Question 54

When determining the sample size needed to achieve a particular error estimate you need
to know . What are two methods of estimating if σ is unknown?

Question 55

Question 56

Question 57

Define margin of error. Explain the relation between the confidence interval and the margin of
error. Suppose a confidence interval is 9.65 < < 11.35. Redefine the confidence interval
into a format using the margin of error and the point estimate of the population mean.

Question 58

Describe the steps for finding a confidence interval.

Question 59

Define in as clear language as possible how a 95% confidence interval can be used for
hypothesis tests.

Question 60

Bert constructed a confidence interval to estimate the mean weight of students in his class.
The population was very small - only 30. Ruth constructed a confidence interval for the mean
weight of all adult males in the city. She based her confidence interval on a very small
sample of only 5. Which confidence interval is likely to give a better estimate of the mean it is
estimating? Which is likely to be more of a problem, a small sample or a small population?