Construct a 98% confidence interval to estimate the average age of all engineers in the company
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A: The objective of this question is to test the claim that there is a significant difference between…
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A study of a random sample of 50 of the technicians conducted in a company that employs 800 technicians shows that the average sample age is 34.30 years. Historically the population standard deviation of the age of the company's employees is approximately 8 years. Construct a 98% confidence
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- From a random sample of 64 high school seniors, the sample mean and standard deviation of the math scores are found to be 90 and 7 respectively. Determine a 92% confidence interval for the mean math score of all seniors in the school and interpret your results. Please help me. Thank youAssume the average amount of caffeine consumed daily by adults is normally distributed with a mean of 260 mg and a standard deviation of 48 mg. In a random sample of 600 adults, how many consume at least 320 mg of caffeine daily?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 37 randomly selected people who train in groups, and finds that they run a mean of 47.7 miles per week. Assume that the population standard deviation for group runners is known to be 3.3 miles per week. She also interviews a random sample of 49 people who train on their own and finds that they run a mean of 49.4 miles per week. Assume that the population standard deviation for people who run by themselves is 4.4 miles per week. Test the claim at the 0.10 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.
- Suppose that the distance of fly balls hit to the outfield (in baseball) is normally distributed with a mean of 260 feet and a standard deviation of 50 feet. We randomly sample 49 fly balls. -Find the 70th percentile of the distribution of the average of 49 fly ballsIn a job fair, 3000 applicants applied for a job. Their mean age was formed to be 28 with a standard deviation of 4 years. Draw a normal curve distribution showing the z scores and the raw scores.A survey reported that in a recent year, the mean serum cholesterol level in milligrams per deciliter for U.S. adults was 198 with a standard deviation of 43. A random sample of 110 adults was chosen. What is the probability that the mean cholesterol level is between 193 and 202?
- You would like to estimate the variance of sick days at a Fortune 500 company. You randomly select 15 employees and record how many sick days they have used in the past year and you get a sample standard deviation of 1.2. Provide a 95% confidence interval estimate of the population variance.A random sample of 47 cars in the drive-thru of a popular fast food restaurant revealed an average bill of $17.51 per car. The population standard deviation is $6.05. Estimate the mean bill for all cars from the drive thru with 91% confidence.Loretta, who turns 91 this year, has heard that the mean systolic blood pressure among the elderly is 120 millimeters of mercury (mm Hg), but she believes that the actual value is higher. She bases her belief on a recently reported study of 19 randomly selected, elderly adults. The sample mean systolic blood pressure of the adults in the study was 121 mm Hg , and the sample standard deviation was 20 mm Hg. Assume that the population of systolic blood pressures of elderly adults is normally distributed. Based on the study, at the 0.1 level of significance, can it be concluded that μ , the mean systolic blood pressure among elderly adults, is greater than 120 mm Hg? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specified in the table. (a) State the null hypothesis H0? and the alternative hypothesis H1? . H0:? H1:? (b) Determine the type of test statistic to…
- Bone mineral density (BMD) is a measure of bone strength. Studies show that BMD declines after age 45. The impact of exercise may increase BMD. A random sample of 59 women between the ages of 41 and 45 with no major health problems were studied. The women were classified into one of two groups based upon their level of exercise activity: walking women and sedentary women. The 39 women who walked regularly had a mean BMD of 5.96 with a standard deviation of 1.22. The 20 women who are sedentary had a mean BMD of 4.41 with a standard deviation of 1.02. Which of the following inference procedures could be used to estimate the difference in the mean BMD for these two types of womenEvery 2 years, the National Assessment of Educational Progress (NAEP) assesses nationally representative samples of students in public and private schools. The NAEP sample of 1077 students in grade 8 in public schools had a mean quantitative score = 275. Because the sample size is large, the sample s is close to the population standard deviation, σ, so take σ = 60. Give a 95% confidence interval for the mean score μ in the population of all young adults. Remember, we are now calculating a range of probable values around our estimate, with Confidence Interval = mean +/- z * (σ / sqrt(n) ), where σ / sqrt(n) is the standard error of the sample mean. In the previous question about the NAEP survey, how does changing the sample size affect the margin of error of a confidence interval? For example, what are the margins of error for samples of size 250, or 4000, compared to 1077?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…
