Quiz 4_ Attempt review _ Courses 2023-2024

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3/28/24, 1:12 PM Quiz 4: Attempt review | Courses 2023-2024 https://moodle-courses2324.wolfware.ncsu.edu/mod/quiz/review.php?attempt=1608953&cmid=955464 1/5 Started on Friday, February 2, 2024, 4:21 PM State Finished Completed on Sunday, February 4, 2024, 7:15 PM Time taken 2 days 2 hours Points 4.25/10.00 Grade 42.50 out of 100.00 Question 1 Incorrect 0.00 points out of 1.00 Question 2 Correct 1.00 points out of 1.00 55% of all internet sites are in English. If we randomly select 21 websites, what do we know about the distribution of the sample proportion of English language websites? a. We CANNOT determine that the distribution will be approximately Normal. b. We can determine that the distribution of the parent population will be approximately Normal, but not the sampling distribution . c. The CAN determine that the distribution will be approximately Normal.  d. The distribution will be symmetric but not Normal. Your answer is incorrect. The correct answer is: We CANNOT determine that the distribution will be approximately Normal. In America, 53% of people leave a tip for their hairdresser. Suppose a random sample of 300 Americans is selected and 65% of those 300 leave a tip for their hairdresser. Which of the following is true? a. The mean of the sampling distribution for the sample proportion with n = 100 depends on whether the distribution is Normal. b. The mean of the sampling distribution for the sample proportion with n = 100 is 0.65. c. The mean of the sampling distribution for the sample proportion with n = 100 is 0.53.  d. The mean of the sampling distribution for the sample proportion with n = 100 is 159. e. The mean of the sampling distribution for the sample proportion with n = 100 is 195. Your answer is correct. The correct answer is: The mean of the sampling distribution for the sample proportion with n = 100 is 0.53.

3/28/24, 1:12 PM Quiz 4: Attempt review | Courses 2023-2024 https://moodle-courses2324.wolfware.ncsu.edu/mod/quiz/review.php?attempt=1608953&cmid=955464 2/5 Question 3 Correct 1.00 points out of 1.00 Question 4 Incorrect 0.00 points out of 1.00 The United States Postal Service (USPS) delivered 32% of all packages shipped in the US in the year 2022. In 2015, USPS delivered 40% of all packages. Which of the following statements about the standard deviation of the sample proportion (that is, ) are correct? Select all that apply. a. For the standard deviation of the sample proportion for 2022 to be equal to that in 2015, the sample sizes must be the same. b. The standard deviation of the sample proportion for a sample of 100 packages in 2022 will be smaller than for a sample of 400 packages in 2022. c. The standard deviation of the sample proportion of packages shipped by USPS for 2022 is smaller than the standard deviation of the parent population.  d. If we randomly select 100 packages from 2022 and 100 package from 2015, the standard deviation of the sample proportion will be larger for 2015.  Your answer is correct. The correct answers are: If we randomly select 100 packages from 2022 and 100 package from 2015, the standard deviation of the sample proportion will be larger for 2015. , The standard deviation of the sample proportion of packages shipped by USPS for 2022 is smaller than the standard deviation of the parent population. A UPS delivery man makes 55 stops along his daily route. The probability that someone is home when he makes a delivery is 0.35. Assume independence. Of 55 randomly selected delivery stops, how many can we expect to have someone home? Answer: 0.660  The correct answer is: 19.25

3/28/24, 1:12 PM Quiz 4: Attempt review | Courses 2023-2024 https://moodle-courses2324.wolfware.ncsu.edu/mod/quiz/review.php?attempt=1608953&cmid=955464 3/5 Question 5 Incorrect 0.00 points out of 1.00 Question 6 Correct 1.00 points out of 1.00 A study found that smartphones made by a particular manufacturer had a failure rate of 43%. Sixteen smartphones made by this manufacturer are randomly selected. The number of phones tested before the first failure is recorded. Are the conditions for a binomial experiment met? Select all that apply. Select one or more: a. No - the random variable does not count successes b. No - there is not a fixed number of trials c. No - the distribution is not bell-shaped d. No - there are not two possible outcomes e. Yes - all conditions are met  Your answer is incorrect. The correct answers are: No - the random variable does not count successes, No - there is not a fixed number of trials According to a recent study, 32% of working adults have a short commute to their jobs. In a random sample of 85 working adults, how much does the sample proportion of working adults with a short commute vary (i.e. what is the standard error)? Round your answer to 4 decimal places. Answer: 0.0506  The correct answer is: 0.0506

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3/28/24, 1:12 PM Quiz 4: Attempt review | Courses 2023-2024 https://moodle-courses2324.wolfware.ncsu.edu/mod/quiz/review.php?attempt=1608953&cmid=955464 4/5 Question 7 Incorrect 0.00 points out of 1.00 Question 8 Correct 1.00 points out of 1.00 The results of a recent survey indicate that when grilling, 59% of all households in the US use a gas grill. Assume you randomly select 100 households. Find the probability that no more than 50 households use a gas grill. (Round your answer to 3 decimal places) Answer: 0.581  The correct answer is: 0.043 Rotator cuff surgery has about a 90% success rate. In a sample of 128 patients undergoing rotator cuff surgery, would it be unusual if only 110 were successful? Select one: a. Yes, because the probability of 110 successes is less than 5% b. No, because the probability of 110 or fewer successes is greater than 5% c. No, because 110 is within 2 standard deviations of the mean number of successes.  d. Yes, because 110 is beyond 2 standard deviations of the mean number of successes. e. No, because this is only a sample and outcomes from samples vary. f. Yes, because 90% of 128 is 115 successes. So 110 is too small. Your answer is correct. The correct answers are: No, because the probability of 110 or fewer successes is greater than 5%, No, because 110 is within 2 standard deviations of the mean number of successes.

3/28/24, 1:12 PM Quiz 4: Attempt review | Courses 2023-2024 https://moodle-courses2324.wolfware.ncsu.edu/mod/quiz/review.php?attempt=1608953&cmid=955464 5/5 Question 9 Incorrect 0.00 points out of 1.00 Question 10 Partially correct 0.25 points out of 1.00 A UPS delivery man makes 50 stops along his daily route. The probability that someone is home when he makes a delivery is 0.35. Assume independence. Find the probability that more than 24 people are home when he makes his deliveries. (Round your answer to 3 decimal places) Answer: 0.660  The correct answer is: 0.021 All G-rated, animated feature films released between 1937 and 1997 by 5 major production companies (Walt Disney Co, MGM/United Artists, Warner Brothers Studios, Universal Studios, and 20th Century Fox) that were available on videotape were reviewed for episodes of tobacco and alcohol use. 68% displayed at least 1 episode of tobacco or alcohol use. A random sample of 20 G-rated, animated films are selected. Which of the following statements are true? ( select all that are true) Select one or more: a. The mean of all sample proportions of 20 films is equal to 17 b. The mean of all sample proportions of 20 films is equal to 0.68  c. We cannot approximate the distribution of the sample proportion with a Normal distribution d. We can approximate the distribution of the sample proportion with a Normal distribution whose mean is 17 e. We can approximate the distribution of the sample proportion with a Normal distribution whose mean is 0.68  f. The sample proportion of these 20 films is equal to 0.68 Your answer is partially correct. You have correctly selected 1. The correct answers are: The mean of all sample proportions of 20 films is equal to 0.68, We cannot approximate the distribution of the sample proportion with a Normal distribution ◄ ICA 4 Jump to... Week 4 Recap Slides (SHORT!) ►