Shea wants to estimate the difference between two population means and plans to use data collected from two independent=simple random samples of sizes n₁30 and n₂ =:35. She does not know the population standard deviations, so she plans toconstruct a two-sample t-confidence interval for the difference in the two means.Use a t-distribution table to determine the positive t-critical value needed to construct a 99% confidence interval using aconservative estimate of the number of degrees of freedom.Enter the positive critical value precise to three decimal places.t =

We have given the following statement about the t distribution n1= 30 n2= 35 Significance level =…

Answered: Shea wants to estimate the difference…

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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An experiment is assessing the effect of exercise regimen on cholesterol level decrease. A random sample of 45 individuals is selected, and their cholesterol decrease after following the regimen is recorded. These decreases are assumed to be normally distributed with a known variance of 20. The sample mean decrease is found to be 30 units. Calculate the 99% confidence interval for the average cholesterol decrease of all individuals on this regimen.
Import the data from the Hill City Excel file into Minitab.You are trying to predict Price.Note: Mtn View=1 if there is a mountain view, 0 otherwise. The rest of the variables should be self explanatory. 1.Perform an F Test for overall significance of the model 2.Perform a T test for slope for the age variable 3. Find a 95% confidence interval for the slope of the SqFeet variable4. Create a prediction, CI, and PI for 1 new set of x values (any valid numbers you want), and interpret each.5. Run the residual plots and indicate if they show any problems with the model.
It is known that the serum cholesterol level of females is normally distributed and its population variance is 45 mg/100 mL. Researchers decided to estimate the population mean serum cholesterol level. They observed a sample average serum cholesterol level of 220 mg/ml in 35 females. a. Compute a 95% confidence interval for the population mean serum cholesterol level of females. b. Researchers at another university are going to collect new data and they are assuming that the female serum cholesterol level is Normally distributed with a population variance of 45. How many subjects do they have to observe to have a 95% confidence interval with a final length of at most 3?
A paint manufacturer wants to introduce a new paint on the market. The following data were obtained for drying time (minutes) when five samples of the paint were tested. 380 290 240 310 300 Assuming that the drying time is normally distributed with a variance of 400, obtain a 99% confidence interval for the true mean drying time.
A consumer advocate wants to collect a sample of jelly jars and measure the actual weight of the product in the container. He needs to collect enough data to construct a confidence interval with a margin of error of no more than 5 grams with 90% confidence. The standard deviation of these jars is usually 6 grams. Estimate the minimum sample size required. The minimum sample size required is nothing jars.
Given two independent random samples with the following results: n1=12x‾1=73s1=27n1=12x‾1=73s1=27 n2=12x‾2=102s2=22n2=12x‾2=102s2=22 Use this data to find the 95%95% confidence interval for the true difference between the population means. Assume that the population variances are equal and that the two populations are normally distributed. Step 1 of 3 : Find the point estimate that should be used in constructing the confidence interval.
A company that manufactures baseball bats believes that its new bat will allow players to hit the ball 30 feet farther than its current model. The owner hires a professional baseball player known for hitting home runs to hit ten balls with each bat and he measures the distance each ball is hit to test the company's claim. The results of the batting experiment are shown in the following table. Construct a 90 % confidence interval for the true difference between the mean distance hit with the new model and the mean distance hit with the older model. Assume that the variances of the two populations are the same. Let Population 1 be the distances of balls hit with the new model baseball bat and Population 2 be the distances of balls hit with the old model. Round the endpoints of the interval to one decimal place, if necessary. Hitting Distance (in Feet) New Model Old Model 215 234 202 298 224 294 211 246 215 268 248 211 255 226 228 284 247 221 214 259
An important problem in industry is shipment damage. A windshield factory ships its product by truck and determines that it cannot meet its profit expectations if, on average, the number of damaged items per truckload is greater than 12. A random sample of 12 departing truckloads is selected at the delivery point and the average number of damaged items per truckload is calculated to be 11.3 with a calculated sample of variance of 0.49. Select a 99% confidence interval for the true mean of damaged items.
Researchers want to test a new hand exercise plan for arthritis patients to see if they have improved flexibility. They recruited 110 patients with arthritis in their hands and randomly assigned them to one of two treatment groups: group i took their regular medicine and did the new hand exercises; and group 2 only took medicine. After one month, 42 of the 55 in group 1 improved in their flexibility, and 37 of the 55 in group 2 improved their flexibility. Based on the 95% confidence interval (-0.076, 0.258), is there convincing evidence of a difference in the proportion of patients like these who would show improvement in flexibility if they did the new hand exercises along with taking the medicine versus just taking the medicine? v to believe there va difference in the proportion of patients like these who would show improvement in flexibility if they did the new hand exercises along with taking the medicine versus just taking the medicine. Because v contained in the interval, there…
One study compared the differences between the expected values of two groups, i.e. tested the null hypothesis that the expected values are equal. The sample size of the first group (x-observations) was 55 and the sample size of the second group (y-observations) was 60. The following data was obtained.X=113.6, Y= 111.7S2x=32.4S2y=30.1Assume large sample sizes and use a test size and two-tailed test appropriate for this setting. Calculate the p-value of the test. Give the answer to two decimal places. Remember the correct decimal separator.
A company that manufactures baseball bats believes that its new bat will allow players to hit the ball 30 feet farther than its current model. The owner hires a professional baseball player known for hitting home runs to hit ten balls with each bat and he measures the distance each ball is hit to test the company's claim. The results of the batting experiment are shown in the following table. Construct a 90 % confidence interval for the true difference between the mean distance hit with the new model and the mean distance hit with the older model. Assume that the variances of the two populations are the same. Let Population 1 be the distances of balls hit with the new model baseball bat and Population 2 be the distances of balls hit with the old model. Round the endpoints of the interval to one decimal place, if necessary. Hitting Distance (in Feet) New Model 246 240 272 262 237 250 247 235 261 216 Old Model 293 232 299 279 239 228 256 292 272 298

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