1 Compute the critical value z Subscript alpha divided by 2

z/2 that corresponds to a 80

80% level of confidence.

z Subscript alpha divided by 2

z/2 =

(Round to two decimal places asneeded.)

2 Determine the point estimate of the populationproportion, the margin of error for the following confidenceinterval, and the number of individuals in the sample with the specifiedcharacteristic, x, for the sample size provided.

Lower boundequals

=0.474

0.474, upper boundequals

=0.826

0.826, nequals

=1500

1500

The point estimate of the population proportion is

nothing

.

(Round to the nearest thousandth asneeded.)

3 Construct a confidence interval of the population proportion at the given level of confidence.

x equals

x=120

120, n equals

n=1200

1200, 90

90% confidence

The lower bound of the confidence interval is

(Round to three decimal places asneeded.)

4 In a survey of 2075

2075 adults in a certain country conducted during a period of economicuncertainty, 66

66% thought that wages paid to workers in industry were too low. The margin of error was 5

5 percentage points with 90

90% confidence. For parts(a) through(d) below, which represent a reasonable interpretation of the surveyresults? For those that are notreasonable, explain the flaw.

(a) We are 90

90% confident 66

66% of adults in the country during the period of economic uncertainty felt wages paid to workers in industry were too low.

Is the interpretationreasonable?

A.

The interpretation is reasonable.

B.

The interpretation is flawed. The interpretation indicates that the level of confidence is varying.

C.

The interpretation is flawed. The interpretation suggests that this interval sets the standard for all the otherintervals, which is not true.

D.

The interpretation is flawed. The interpretation provides no interval about the population proportion.

5 A survey of 2317

2317 adults in a certain large country aged 18 and older conducted by a reputable polling organization found that 413

413 have donated blood in the past two years. Complete parts(a) through(c) below.

(a) Obtain a point estimate for the population proportion of adults in the country aged 18 and older who have donated blood in the past two years.

ModifyingAbove p with caret

pequals

=

nothing

(Round to three decimal places asneeded.)

6 A group conducted a poll of 2036

2036 likely voters just prior to an election. The results of the survey indicated that candidate A would receive 47

47% of the popular vote and candidate B would receive 45

45% of the popular vote. The margin of error was reported to be 3

3%. The group reported that the race was too close to call. Use the concept of a confidence interval to explain what this means.

What does it mean to say the race was too close tocall?

A.

Since the difference between the percentages of the popular vote for the candidates is less than the 8

8% of voters that areundecided, the poll cannot predict the winner.

B.

Since the poll results do not show that one of the candidates has more than50% of the popularvote, the poll cannot predict the winner.

C.

The margin of error suggests candidate A may receive between 44

44% and 50

50% of the popular vote and candidate B may receive between 42

42% and 48

48% of the popular vote. Because the poll estimates overlap when accounting for margin oferror, the poll cannot predict the winner.