2023 Spring Semester Exam

Posljednje ažuriranje about 2 years ago

22 questions

Obavezno

2023 Spring Semester Exam

Posljednje ažuriranje about 2 years ago

22 questions

Obavezno

Ch.5
The standard deviation of the number of puzzles subject could solve is 0.9 and the mean is 7.4 puzzles.
Which of the following is the best interpretation of the standard deviation?

The typical subject solved an average of 7.4 puzzles.

The typical subject solved an average of 0.9 puzzles.

The number of puzzles solved by subjects typically differed from the mean by about 0.9 puzzles.

About 95% of subjects solved between 1.8 puzzles less than and 1.8 puzzles more than the mean.

The number of puzzles solved by subjects typically differed from one another by about 0.9 puzzles.

Obavezno

Ch.5
Professional tennis player Novak Djokovic hits the ball extremely hard. His first-serve speeds follow a normal distribution with mean 112 miles per hour (mph) and
standard deviation of 6 mph.
Let X = the speed of one of Djokovic’s first serves at random, measured in miles per hour.
A first serve with a speed less than 100 miles per hour is considered “slow.”
What percent of Djokovic’s first serves are slow?

Hint: 1st calculate the z score
2nd use the z chart
Enter your answer as a decimal rounded to four places or a percent rounded to two places past the decimal point.

Obavezno

Ch.5
Professional tennis player Novak Djokovic hits the ball extremely hard. His first-serve speeds follow a normal distribution with mean 112 miles per hour (mph) and
standard deviation of 6 mph.
Let X = the speed of one of Djokovic’s first serves at random, measured in miles per hour.
Calculate P(x > 120), this means find the probability that Djokovic's first serve is greater than 120 mph. Include four places past the decimal.
Hint: 1st calculate the z score,
2nd use the blue table, think about what direction you are interested in.

Obavezno

Ch.6
A Gallup study on voting chose 663 registered voters at random shortly after an election. Of these, 72% said they had voted in the election.
Election records based on the community show that only 56% of all registered voters voted in the election.
Match the following items:

Stavka koja se može prevući		Odgovarajuća stavka
663 registered voters		Parameter, calculated on the population
72%		Population
56%		Statistic, calculated on the sample
All registered voters		Sample

Obavezno

Ch.6
A polling organization wants to estimate the proportion of voters who favor a new law banning smoking in public buildings. The organization decides to increase the size of its random sample of voters from about 1500 people to about 4000 people right before an election.
The effect of this increase in sample size is to

increase the margin of error of the estimate.

increase the bias of the estimate.

reduce the bias of the estimate.

reduce the margin of error of the estimate.

Obavezno

Ch.6
The student newspaper at a large university asks an SRS of 250 undergraduates, “Do you favor eliminating the carnival from the end-of-term celebration?”
Suppose that 55% of all undergraduates favor eliminating the carnival.
For a sampling distribution of proportions, which of the following is closest to the probability of getting less than 50% in favor of eliminating the carnival in a random sample of size 250?
Use the Ch. 6 formula chart to calculate the z-score, then use the z chart.

Obavezno

Ch.7
In a recent Gallup poll of randomly selected U.S. adults, 75% said they would vote for a law that imposed term limits on members of the U.S. Congress.
The poll’s margin of error was 4 percentage points at the 95% confidence level. This means that...
Hint: remember the interpretation of a confidence interval

the poll used a method that gets an answer within 4 percentage points of the truth about the population 95% of the time.

if Gallup takes another poll on this issue, the results of the second poll will lie between 71% and 79%.

there is convincing evidence that more than 79% of all U.S. adults would vote for term limits.

Gallup can be 95% confident that between 71% and 79% of the adults in the sample would vote for term limits.

Obavezno

Ch.7
A 95% confidence interval for p, the proportion of all shoppers at a large grocery store who purchase cookies, is 0.236 to 0.282.
The point estimate and margin of error for this interval are:

Point estimate = 0.259; Margin of error = 0.046.

Point estimate = 0.236; Margin of error = 0.282.

Point estimate = 0.236; Margin of error = 0.046.

Point estimate = 0.259; Margin of error = 0.023.

Obavezno

Ch.7
A quality control manager at a manufacturing plant wants to estimate the mean length of metal rods produced by a certain machine.
The manager is deciding between a 95% confidence level and a 99% confidence level. Compared to a 95% confidence interval, a 99% confidence interval will be...
Hint: read carefully, ex. a smaller risk of being incorrect is a larger confidence of being correct.

narrower and would involve a larger risk of being incorrect.

narrower and would involve a smaller risk of being incorrect.

wider and would involve a larger risk of being incorrect.

wider and would involve a smaller risk of being incorrect.

Obavezno

Ch.7
A quality control manager at a manufacturing plant wants to estimate the mean length of metal rods produced by a certain machine.
The researcher wants to create a 95% confidence interval and is deciding between a sample of size n = 500 and a sample of size n = 1000.
Compared to using a sample size of n = 500, a 95% confidence interval based on a sample size of n = 1000 will be...

narrower and would involve a smaller risk of being incorrect (smaller confidence level).

wider and would involve a smaller risk of being incorrect (smaller confidence level).

narrower and would involve a larger risk of being incorrect (larger confidence level).

narrower and would involve the same risk of being incorrect (same confidence level).

Obavezno

Ch.7
Most people can roll their tongues, but some can’t.
Suppose we are interested in determining what proportion of people in a certain population can roll their tongues.
We test a random sample of 80 people from this population and find that 64 can roll their tongues.
Find the point estimate and margin of error for a 95% confidence interval for the true proportion of tongue rollers in this population is closest to...
Hint: 1st find p-hat
2nd calculate the margin of error, check your formula chart for Ch. 7

P.E. = 0.8, M.E. = 0.088.

P.E. = 0.64, M.E. = 0.088.

P.E. = 0.64, M.E. = 0.045.

P.E.= 0.8, M.E. = 0.045

Obavezno

Ch. 7
Does the confidence interval in the previous question support Pauly's Pizza claim that it takes 30 minutes on average to deliver a pizza?
Select both correct answers:

No, the confidence interval does not support Pauly's Pizza claim

because the confidence interval does not capture the claim of 30.0 minutes.

the confidence interval captures the claim of 30.0 minutes.

Yes, the confidence interval supports Pauly's Pizza claim

Obavezno

Ch.8
You survey selected members of a population that is approximately normally distributed and test the hypotheses
Ho: p = 0.86
Ha: p > 0.86
At the alpha = 0.05 significance level, you obtain a P-value of 0.062.
Which 3 of the following statements are true?

There is some evidence for the Ha from your sample, but there is not convincing evidence for Ha.

You fail to reject the Ho.

because the P-value is greater than the alpha level

You have failed to obtain any evidence for Ha, the sample mean = the population mean.

You can reject Ho.

You have convincing evidence that the Ho is not true and the Ha is true.

You have convincing evidence that Ha is true.

because the P-value is less than the alpha level

Obavezno

Ch. 8
A fresh fruit distributor claims that only 4% of his Macintosh apples are bruised.
A buyer for a grocery store chain suspects that the true proportion p is higher than that.
She takes a random sample of 30 apples to test the null and alternative hypotheses
Ho: p = 0.04 Ha: p > 0.04
Which of the following statements about conditions for performing a one-sample z test for the population proportion is correct?
Hint: Check the conditions first.

All conditions for performing the test have been met.

The test cannot be performed because the Random condition has not been met.

We can’t determine if the conditions have been met until we have the sample proportion.

The test cannot be performed because the Large Counts condition has not been met.

Obavezno

Ch. 8
As a construction engineer for a city, you are responsible for ensuring that the company that is providing gravel for a new road puts as much gravel in each truckload as they claim.
Each truckload is supposed to have 20 cubic meters of gravel, so you will test the hypotheses Ho: μ = 20 versus
Ha: μ < 20
at the α = 0.05 level.
Describe a Type I error in this setting.

The trucks have the correct amount and you decide that they have less than the correct amount.

The trucks have the correct amount and you agree that they do have the correct amount.

The trucks have less than the correct amount and you agree that they have less than the correct amount.

The trucks have less than the correct amount and you decide that they do have the correct amount.

Obavezno

The recommended daily allowance (RDA) of calcium for women between the ages of 18 and 24 years is 1200 milligrams (mg).
Researchers who were involved in a large-scale study of women’s bone health suspected that their participants had significantly lower calcium intakes than the RDA.
To test this suspicion, the researchers measured the daily calcium intake of a random sample of 36 women from the study who fell in the desired age range.
The sample mean was 856.2 mg and the standard deviation was 306.7 mg.
Calculate the standardized test statistic for the significance test of the mean calcium intake.
Round your answer to three places past the decimal.

Obavezno

2023 Spring Semester Exam

2023 Spring Semester Exam

Ch.5The standard deviation of the number of puzzles subject could solve is 0.9 and the mean is 7.4 puzzles. Which of the following is the best interpretation of the standard deviation?

Ch.6A Gallup study on voting chose 663 registered voters at random shortly after an election. Of these, 72% said they had voted in the election. Election records based on the community show that only 56% of all registered voters voted in the election. Match the following items:

Ch.7A 95% confidence interval for p, the proportion of all shoppers at a large grocery store who purchase cookies, is 0.236 to 0.282. The point estimate and margin of error for this interval are:

Ch. 7Does the confidence interval in the previous question support Pauly's Pizza claim that it takes 30 minutes on average to deliver a pizza?Select both correct answers:

Ch.8You survey selected members of a population that is approximately normally distributed and test the hypotheses Ho: p = 0.86 Ha: p > 0.86 At the alpha = 0.05 significance level, you obtain a P-value of 0.062. Which 3 of the following statements are true?

Ch.5The standard deviation of the number of puzzles subject could solve is 0.9 and the mean is 7.4 puzzles. Which of the following is the best interpretation of the standard deviation?

Ch.6A Gallup study on voting chose 663 registered voters at random shortly after an election. Of these, 72% said they had voted in the election. Election records based on the community show that only 56% of all registered voters voted in the election. Match the following items:

Ch.7A 95% confidence interval for p, the proportion of all shoppers at a large grocery store who purchase cookies, is 0.236 to 0.282. The point estimate and margin of error for this interval are:

Ch. 7Does the confidence interval in the previous question support Pauly's Pizza claim that it takes 30 minutes on average to deliver a pizza?Select both correct answers:

Ch.8You survey selected members of a population that is approximately normally distributed and test the hypotheses Ho: p = 0.86 Ha: p > 0.86 At the alpha = 0.05 significance level, you obtain a P-value of 0.062. Which 3 of the following statements are true?

Ch.5
The standard deviation of the number of puzzles subject could solve is 0.9 and the mean is 7.4 puzzles.
Which of the following is the best interpretation of the standard deviation?

Ch.6
A Gallup study on voting chose 663 registered voters at random shortly after an election. Of these, 72% said they had voted in the election.
Election records based on the community show that only 56% of all registered voters voted in the election.
Match the following items:

Ch.7
A 95% confidence interval for p, the proportion of all shoppers at a large grocery store who purchase cookies, is 0.236 to 0.282.
The point estimate and margin of error for this interval are:

Ch. 7
Does the confidence interval in the previous question support Pauly's Pizza claim that it takes 30 minutes on average to deliver a pizza?
Select both correct answers:

Ch.8
You survey selected members of a population that is approximately normally distributed and test the hypotheses
Ho: p = 0.86
Ha: p > 0.86
At the alpha = 0.05 significance level, you obtain a P-value of 0.062.
Which 3 of the following statements are true?

Ch.5
The standard deviation of the number of puzzles subject could solve is 0.9 and the mean is 7.4 puzzles.
Which of the following is the best interpretation of the standard deviation?

Ch.6
A Gallup study on voting chose 663 registered voters at random shortly after an election. Of these, 72% said they had voted in the election.
Election records based on the community show that only 56% of all registered voters voted in the election.
Match the following items:

Ch.7
A 95% confidence interval for p, the proportion of all shoppers at a large grocery store who purchase cookies, is 0.236 to 0.282.
The point estimate and margin of error for this interval are:

Ch. 7
Does the confidence interval in the previous question support Pauly's Pizza claim that it takes 30 minutes on average to deliver a pizza?
Select both correct answers:

Ch.8
You survey selected members of a population that is approximately normally distributed and test the hypotheses
Ho: p = 0.86
Ha: p > 0.86
At the alpha = 0.05 significance level, you obtain a P-value of 0.062.
Which 3 of the following statements are true?