Note that when the population variance is 20, the population standard deviation is 4.47. So the answer tod is also the answer to a case where the standard deviation is 4.47.d. Suppose the standard deviaiton is 8.94 (twice as large as 4.47). What is minimum sample size neededto create a 90% confidence interval that is 1 unit wide?e. Is the increase in the minimum sample size proportional to the 2x increase in the standard deviation(compare the answer to e to the answer to d)? Why or why not?f. Is an increase in the minimum sample size proportional to an increase in the variance (compare theanswer to a to the answer to b)? Why or why not? 8. Suppose you need to compute a 90% confidence interval for a population

Determination of sample size for estimation of mean.

Answered: Note that when the population variance…

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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If the standard error of the mean is σx̅ = 3 and the sample size is n = 64, then the population standard deviation is?
Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 33 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 5.9 and a standard deviation of 3.4. What is the 90% confidence interval for the number of chocolate chips per cookie for Big Chip cookies? With 90% confidence, we can say the true population mean of chocolate chips per cookie in Big Chip cookies is between_____ and_____ .Use 1 decimal place.
For a normally distributed population with a mean of 35 and a standard deviation of 7.5, what value of X would be exceeded only 5% of the time?
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Suppose you take a sample of size 60 from a Normal distribution with population mean (mu) 412 and population standard deviation (sigma) of 18. Suppose your sample yields a sample mean (x-bar) of 406. What is the margin of error for a 95% confidence interval for mu?
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An ecologist is studying the impact of local polluted waters on the growth of alligators. The length of adult male alligators typically follows a normal distribution with a standard deviation of 2 feet. The ecologist wants to estimate the mean length of this population of alligators. Suppose she samples n alligators at random and uses the sample mean, X to as an estimator for u. a. What is the bias and variance of the estimator? (Note, these may be a function of n.) b. If n = 4, what is the probability that the estimator is within one foot of the true mean? (I.e. find P(|X – µ| < 1). c. What sample size, n, is required for the estimator to be within one foot of the true mean with 95% probability? (I.e. find the value of n that satisfies P(|X – µ| < 1) = 0.95.) d. Suppose the ecologist ends up sampling n = 9 alligators and calculates a sample mean of ī = 10.4 feet. Construct a 95% confidence interval for the population mean. e. Give an interpretation for the interval obtained in (d).
The mean IQ for the entire population in any age group is known to be 100 with a standard deviation of 15. Suppose the IQ scores of 72 12th graders in Columbus are measured and the sample mean is found to be 103.4 and the sample standard deviation is 20.2. Do the scores provide good evidence that the mean IQ of this population is not 100? State the null (H0) and alternative (Ha) hypotheses. 2. What are the confidence intervals for this data? 3. What is the value of the test statistic? 4. What is the p-value for this data? 5. What is your decision about the null hypothesis?: Reject Fail to Reject 6. Summarize the conclusion in the context of the problem.
Q1. A survey of 345 men showed that the mean time spent on daily grocery shopping is 15 mins. From previous record we knew that o = 3 mins. Find the 98% confidence interval for population mean. Q2. A poll of 140 students shows that the mean time spent weekly on cloths laundry is 150 mins. We don't have previous record on population standard deviation, and so from the sample we computed sample standard deviation and found that s = 10 mins. Find the 95% confidence interval for the population mean.
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Mrs. Gallas wanted to estimate the average weight of an Oreo cookie to determine if theaverage weight was less than advertised. She selected a random sample of 30 cookies andfound the weight of each cookie (in grams). The mean weight was = 11.1921 grams with astandard deviation of sx = 0.0817 grams. Make a 95% confidence interval to estimate the truemean weight of an Oreo. 1. What is the formula for calculating the standard deviation of the sampling distribution of x? 2.What condition must be met to use this formula? Has it been met?
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