Telephone Calls A researcher knew that before cell phones, a personmade on average 2.5 calls per day. He believes that the number of callsmade per day today is higher. He selects a random sample of 32 individualswho use a cell phone and asks them to keep track of the number of callsthat they made on a certain day. The mean was 2.8. At α=0.05, is there enoughevidence to support the researcher's claim? The standard deviation for thepopulation found by a previous study is 0.6. Assume that the variable isnormally distributed. Use the critical value method with tables. State the hypotheses and identify the claim with the correct hypothesis.Ho: (Choose one) ▼H₁:(Choose one) ▼This hypothesis test is a (Choose one) test.

The sample size is 32, sample mean is 2.8, population standard deviation is 0.6.

Answered: Telephone Calls A researcher knew that…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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In a school district, all sixth grade students take the same standardized test. The superintendant of the school district takes a random sample of 30 scores from all of the students who took the test. She sees that the mean score is 169 with a standard deviation of 7.0674. The superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 13. Is there evidence that the standard deviation of test scores has decreased at the α=0.005 level? Assume the population is normally distributed. Step 4: Make a decision. Is it reject Null hypothesis or Fail to reject Null hypothesis? Step 5: What is the conclusion? Is there sufficient evidence or there is not sufficient evidence to show that the standard deviation of the test scores has decreased?
Suppose that El Camino is studying the average number of hours students study for classes per week. According to research from 2010 El Camino students spent an average of 21 hours a week studying for classes. El Camino wants to study if this average has changed. To do this they take a random sample of 81 current students and find that the average student spent 19.3 hours studying with a standard deviation of 6.4 hours. (Note: You may assume there are approximately 20,000 El Camino students). (a) Carry out a hypothesis test at α = .05 to test the claim that the average number of hours per week that El Camino students study has changed since 2010. (b) Describe what it would mean in this situation to make a Type I error (c) Describe what it would mean in this situation to make a Type II error (d) Construct a 95% confidence interval for the average number of hours studied by El Camino students per week. Make sure to interpret your interval.
Telephone Calls A researcher knew that before cell phones, a person made on average 2.9 calls per day. He believes that the number of calls made per day today is higher. He selects a random sample of 28 individuals who use a cell phone and asks them to keep track of the number of calls that they made on a certain day. The mean was 3.1. At =α0.10, is there enough evidence to support the researcher's claim? The standard deviation for the population found by a previous study is 0.7. Assume that the variable is normally distributed. Use the critical value method with tables. State the hypotheses and identify the claim with the correct hypothesis. :H0 =μ2.9 ▼not claim :H1 >μ2.9 ▼claim This hypothesis test is a ▼one-tailed test. Part 2 of 5************************************************************* Find the critical value(s). Round the answer to two decimal places. If there is more than one critical value, separate them with commas. Critical…
Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 42 randomly selected people who train in groups and finds that they run a mean of 47.1 miles per week. Assume that the population standard deviation for group runners is known to be 4.4 miles per week. She also interviews a random sample of 47 people who train on their own and finds that they run a mean of 48.5 miles per week. Assume that the population standard deviation for people who run by themselves is 1.8 miles per week. Test the claim at the 0.01 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.
On average, a banana will last 6.3 days from the time it is purchased in the store to the time it is too rotten to eat. The standard deviation is 2.1 days. Will the average banana spoil earlier if the banana is hung from the ceiling? The data show results of an experiment with 16 bananas that are hung from the ceiling. Assume that that distribution of the population is normal. 5, 8, 5, 7, 4, 4, 6, 8, 6, 7, 5, 7, 6, 3, 6,2 What can be concluded at the 0.10 level of significance? H0: = 6.3 Ha: [ Select ] [">", "<", "Not Equal To"] 6.3 Test statistic:[ Select ] ["T", "Z"] p-Value = [ Select ] ["0.02", "0.08", "0.04", "0.16"] [ Select ] ["Reject Ho", "Fail to Reject Ho"] Conclusion: There is [ Select ] ["insufficient", "statistically significant"] evidence to make the conclusion that the population mean time that it takes for bananas to spoil if they are hung from the ceiling is less than 6.3 days.
In a school district, all sixth grade students take the same standardized test. The superintendant of the school district takes a random sample of 3030 scores from all of the students who took the test. She sees that the mean score is 169169 with a standard deviation of 7.06747.0674. The superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 1313. Is there evidence that the standard deviation of test scores has decreased at the α=0.005α=0.005 level? Assume the population is normally distributed. Step 1 of 5: State the null and alternative hypotheses. Round to four decimal places when necessary. Step 2 of 5: Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places. Step 3 of 5: Determine the value of the test statistic. Round your answer to three decimal places. Step 4 of 5: Make the…
For a sample, a score that is 12 points above the mean has a z-score of z = 1.20. What is the sample standard deviation?
Steve believes that his wife's cell phone battery does not last as long as his cell phone battery. On eight different occasions, he measured the length of time his cell phone battery lasted and calculated that the mean was 19.7 hours with a standard deviation of 9.4 hours. He measured the length of time his wife's cell phone battery lasted on twelve different occasions and calculated a mean of 18.9 hours with a standard deviation of 5.3 hours. Assume that the population variances are the same. Let Population 1 be the battery life of Steve's cell phone and Population 2 be the battery life of his wife's cell phone. Step 1 of 2: Construct a 90 % confidence interval for the true difference in mean battery life between Steve's cell phone and his wife's. Round the endpoints of the interval to one decimal place, if necessary.
3 In the 1800s, German physician Carl Reinhold, took millions of axillary (i.e. armpit) temperatures from soldiers. This study established that body temperature is normally distributed and the standard normal human body temperature is 98.6℉ with a standard deviation of 0.72 ℉. In a recent study, American researchers obtained 5,000 axillary temperatures from a Los Angeles hospital. The mean of these temperature readings was 97.9 ℉. Assuming a Type I error risk of no more than 5%, did the findings support the theory that human, body temperature has decreased since the 1800s? What is the standard error? (round to nearest hundredth) What is the Z obt? (round to the nearest tenth)
Workers' Distractions. A recent study showed that the modern working person experiences an average of 2.1 hours per day of distractions (phone calls, e- mails, impromptu visits, etc.). A random sample of 16 workers for a large corporation found that these workers were distracted an average of 1.8 hours per day and the standard deviation was 20 minutes. Estimate the true mean population distraction time with 90% confidence, and compare your answer to the results of the study. (1.654,1.946). Mean of the study is outside or "different" from the result of our study.

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