Listed below are speeds​ (mi/h) measured from traffic on a busy highway. This simple random sample was obtained at​ 3:30 P.M. on a weekday. Use the sample data to construct an 80​% confidence interval estimate of the population standard deviation. 62 64 64 56 64 52 59 58 59 70 58 68 The confidence interval estimate is ___mi/h < σ < ___mi/h.

As part of a water quality​ survey, you test the water hardness in several randomly selected streams. The results are shown below. Construct a confidence interval for the population variance sigma squaredσ2 and the population standard deviation sigmaσ. Use a 90% level of confidence. Assume that the population has a normal distribution.   n =25 s =19 grains per gallon

Use the given data to find the 95% confidence interval estimate of the population mean ?μ. Assume that the population has a normal distribution. IQ scores of professional athletes: Sample size ?=10n=10Mean ?⎯⎯⎯=103x¯=103Standard deviation ?=12s=12 <?<<μ<

A statistics class is estimating the mean height of all female students at their college. They collect a random sample of 42 female students and measure their heights. The mean of the sample is 65.3 inches and the sample standard deviation is 5.4 inches. Find the 90% confidence interval for the mean height of all female students in their school? Assume that the distribution of individual female heights at this school is approximately normal. 1. The t value is 1.3025 2. The standard error has a value of -- 3. The margin of error has a value of 4. Find the 90% confidence interval for the mean height of all female students in their school

A math teacher claims that she has developed a review course that increases the scores of students on the math portion of a college entrance exam. Based on data from the administrator of the exam, scores are normally distributed with H = 525. The teacher obtains a random sample of 2200 students, puts them through the review class, and finds that the mean math score of the 2200 students is 530 with a standard deviation of 119. Complete parts (a) through (d) below. C. Yes, because every increase in score is practically significant. D. No, because the score became only 0.95% greater. (d) Test the hypothesis at the a = 0.10 level of significance with n= 400 students. Assume that the sample mean is still 530 and the sample standard deviation is still 119. Is a sample mean of 530 significantly more than 525? Conduct a hypothesis test using the P-value approach. Find the test statistic. to =0 (Round to two decimal places as needed.) %3D Find the P-value. The P-value is (Round to three decimal…

The mean score on a driving exam for a group of driver’s education students is 76 points, with a standard deviation of 6 points. Apply chebychev’s theorem to the data using K=2. Interpret, At least ___% of the exam score falls between ___and ____

Researchers conducted a study to determine whether magnets are effective in treating back pain. Pain was measured using the visual analog​ scale, and the results shown below are among the results obtained in the study. Higher scores correspond to greater pain levels. Assume that the two samples are independent simple random samples selected from normally distributed​ populations, and do not assume that the population standard deviations are equal. Complete parts​ (a) to​ (c) below.   Reduction in Pain Level After Magnet Treatment ​(μ1​): n=29​, x=0.58​, s=0.95 Reduction in Pain Level After Sham Treatment ​(μ2​): n=29​, x=0.48​, s=1.56       Question content area bottom Part 1 a. Use a 0.05 significance level to test the claim that those treated with magnets have a greater mean reduction in pain than those given a sham treatment​ (similar to a​ placebo).   What are the null and alternative​ hypotheses?     A. H0​: μ1≠μ2 H1​: μ1<μ2   B. H0​: μ1<μ2 H1​:…

The manufacturer of a sports car claims that the fuel injection system lasts 48 months before it needs to be replaced. A consumer group tests this claim by surveying a random sample of 10 owners who had the fuel injection system replaced. The ages of the cars at the time of replacement were (in months): 21 48 45 48 53 46 30 51 42 52 (i) Use your calculator to calculate the mean age of a car when the fuel injection system fails x and standard deviation s. (Round your answers to two decimal places.) x =  months s =  months What is the value of the sample test statistic? (Round your answer to three decimal places.) (c) Find (or estimate) the P-value. P-value > 0.2500.125 < P-value < 0.250    0.050 < P-value < 0.1250.025 < P-value < 0.0500.005 < P-value < 0.025P-value < 0.005 Sketch the sampling distribution and show the area corresponding to the P-value. State the null and alternate hypotheses.

A random sample of 15 exam scores showed a standard deviation of 6.0 points. Find the 95 percent confidence interval for the population standard deviation. Use Appendix E to obtain the values of  χ2LχL2 and χ2UχU2 . (Round your answers to 2 decimal places.) The 95% confidence interval is from ______ to __________  .

Energy drinks: A survey of college students reported that in a sample of 402 male college students, the average number of energy drinks consumed per month was 2.41 with a standard deviation of 3.18, and in a sample of 390 female college students, the average was 1.50 with a standard deviation of 4.77. Part: 0/2 Part 1 of 2 Construct a 80% confidence interval for the difference between men and women in the mean number of energy drinks consumed. Let μ, denote the mean number of energy drinks consumed by men. Use tables to find the critical value and round the answers to at least two decimal places. A 80% confidence interval for the difference between men and women in the mean number of energy drinks consumed is 0<44-₂2 <0. X S Part: 1/2 Part 2 of 2 Based on the confidence interval, is it reasonable to believe that the mean number of energy drinks consumed may be the same for both male and female college students? It (Choose one) reasonable to believe that the mean number of energy drinks…