Question 1

The college daily reported: ?600 students living in university housing were polled. 360 said that they were satisfied with their living conditions. Based on this survey we conclude that 60% of students living in dormitories are satisfied. The margin of error of the study is 4 percentage points (with a 95% degree of confidence). Which statement is correct?
A) There is not enough information to determine whether the margin of error is consistent with the sample size.
B) The stated margin of error could have been achieved with a smaller sample size.
C) A larger sample should be used to achieve the stated margin of error.
D) The margin of error is consistent with the sample size.
104

Accepted Answer

The margin of error of 4 percentage points is consistent with a sample size of 600, given a 95% confidence level.

Question 2

In a poll of 200 voters, 55% said that they supported a local ban on smoking in restaurants. The margin of error was reported as 5%. Which one of the following statements reflects the accuracy of this result?
A) The reported margin of error is consistent with the sample size.
B) There is not enough information to determine whether the margin of error is consistent with the sample size.
C) The sample size is too small to achieve the stated margin of error.
D) For the given sample size, the margin of error should be smaller than stated.

Accepted Answer

The answer of In a poll of 200 voters, 55%...

Question 3

In a national poll, 1036 people were interviewed and asked the question, "Do you think it should be legal to carry a concealed weapon if it is properly registered?". 642 people responded "No." If the city of Upton is typical of the entire U.S., estimate the number of people in this city with a population of 14,642 who would respond "No" to the question.

Accepted Answer

The answer of In a national poll, 1036 people were...

Question 4

A survey of 650 adult males found that 247 of them held current fishing licenses. Find a 95% confidence interval (to three decimal places) for the proportion of all adult males who hold current fishing licenses.

Accepted Answer

The answer of A survey of 650 adult males found...

Question 5

Half of all people with social security numbers (SSNs) have a number that ends with a 0, 2, 4, 6, or 8. A sample of 100 students found that 45 had even numbered SSNs. The sample proportion has a z-score of -1.0. If a second =sample of 100 students is taken, what is the probability that the sample proportion has a z-score less than -1.0?

Accepted Answer

The answer of Half of all people with social security...

Question 6

A population proportion is to be estimated. Estimate the minimum sample size needed to achieve a margin of error of E = 0.056 with a 95% degree of confidence.

Accepted Answer

The answer of A population proportion is to be estimated....

Question 7

A campaign committee expects the next election for mayor to be close. The members want to take a poll to see how their candidate is likely to fare. What is the minimum sample size needed to estimate their candidate's percentage of the vote to within 5%?

Accepted Answer

The answer of A campaign committee expects the next election...

Question 8

In a random sample of 400 jelly beans, there were 88 red ones. What is the sample proportion of red jelly beans?

Accepted Answer

The answer of In a random sample of 400 jelly...

Question 9

The weight (in pounds) of a random sample of 32 new born babies, born at a particular hospital are given below. Estimate the mean weight of the population of new born babies born at this hospital. Give the 95% confidence interval to two decimal places. The sample mean is 7.19 pounds and the standard deviation is 0.844 pounds. $$\begin{array} { l l l l l l l l } 
8.0 & 6.2 & 6.8 & 7.1 & 6.8 & 8.6 & 7.4 & 6.4 \
7.4 & 7.0 & 6.0 & 7.8 & 9.0 & 7.3 & 6.5 & 5.8 \
8.4 & 7.6 & 7.2 & 6.5 & 8.5 & 7.1 & 6.3 & 6.9 \
7.0 & 5.9 & 8.3 & 6.6 & 7.3 & 7.7 & 6.4 & 8.2
\end{array}$$

Accepted Answer

The answer of The weight (in pounds) of a random...

Question 10

A researcher wishes to estimate the proportion of left-handers among a certain population. In a random sample of 900 people from the population, 74% are left-handed. Find the margin of error for the 95% confidence interval.

Accepted Answer

The answer of A researcher wishes to estimate the proportion...

Question 11

A researcher wants to estimate the starting salary of Assistant Professors in Economics with a margin of error of $400 for a 95% confidence interval. If the standard deviation of those salaries is assumed to be $3600, what is the minimum sample size she should use?

Accepted Answer

The answer of A researcher wants to estimate the starting...

Question 12

A random sample of 100 college students had an average student loan of $816. This was 1.3 standard deviations above the mean of the sampling distribution of the sample mean. If another random sample of 100 students were taken, what is the probability that that sample would have a mean greater than $816?

Accepted Answer

The answer of A random sample of 100 college students...

Question 13

If a sample of size 900 has a mean of 452 and a standard deviation of 96, what is the margin of error for a 95% confidence interval?

Accepted Answer

The answer of If a sample of size 900 has...

Question 14

A researcher wishes to estimate the proportion of left-handers among a certain population. In a random sample of 690 people from the population, 16.4% are left-handed. Find the 95% confidence interval for the population proportion of left-handers to four decimal places.

Accepted Answer

The answer of A researcher wishes to estimate the proportion...

Question 15

An internet sales company decided to charge the same amount for shipping and handling on all packages. To determine the amount, they took a random sample of previous sales to determine the average weight. The packages weighed 4, 17, 12, 9, 13, 1, 7, 10, and 8 pounds.
Estimate the population mean weight to the nearest tenth of a pound.

Accepted Answer

The answer of An internet sales company decided to charge...

Question 16

In a poll of 400 U.S. adults, 84 indicated that they did not know how to swim. Find the margin of error E for estimating the proportion of all U.S. adults who cannot swim with a 95% confidence interval.

Accepted Answer

The answer of In a poll of 400 U.S. adults,...

Question 17

During a year when there was a bad flu epidemic, a school district sampled 30 student records to get an estimate of the mean number of absences of all of the students. The absences recorded were 
$\begin{array}{l}
\begin{array}{lllllllllllllll}
1 & 2 & 3 & 3 & 6 & 6 & 6 & 7 & 7 & 7 & 7 & 8 & 11 & 11 & 12\

13&13&14&14&14&15&16&17&18&19&19&21&22&23&25 \
\end{array} \
\end{array}$ 
The sample mean is 12.0 absences and the standard deviation is 6.6384. Find a 95% confidence interval for the population mean to two decimal places..

Accepted Answer

The answer of During a year when there was a...

Question 18

A researcher wants to estimate the mean cost of textbooks per year for students at a large university. He wants a margin of error of $10 for a 95% confidence interval. If the standard deviation of those costs is assumed to be $50, what is the minimum sample size he should use?

Accepted Answer

The answer of A researcher wants to estimate the mean...

Question 19

A sample of 144 college freshmen had a mean mathematics placement test score of 17.82 with a standard deviation of 4.8. Find a 95% CI for the population mean placement score for all freshmen.

Accepted Answer

The answer of A sample of 144 college freshmen had...

Question 20

Stanford-Binet IQ scores have a population mean of 100 and a standard deviation of 16. A community college selects 64 students at random to test and finds that the sample mean is 105.6. What is the z-score associated with this sample mean?

Accepted Answer

The answer of Stanford-Binet IQ scores have a population mean...

Quiz 8: From Samples to Populations

In a poll of 200 voters, 55% said that they supported a local ban on smoking in restaurants. The margin of error was reported as 5%. Which one of the following statements reflects the accuracy of this result?