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As an alternative to imposing unbiasedness, an estimator’s distribution can be “centered” by requiring that its median be equal to the unknown parameter
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An Introduction to Mathematical Statistics and Its Applications (6th Edition)
- The average number of pounds of sliced ham ordered per customer at the deli where Dennis used to work was 1.4, but at his new job, the average of the 32 people who have ordered ham so far is 1.5 pounds, with a standard deviation of 0.3 pounds. a) Write the null and alternative hypotheses to test if the average amount of ham bought is higher at the new store. H0:μ= H1:μ> b) For α=0.025, find the rejection region in terms of z. [Write your answer with 2 decimal places.] R:z≥ c) What test statistic corresponds to an x¯ of 1.5 pounds? [Round your answer to 2 decimal places.] z= d) Should you reject the null hypothesis?arrow_forwardThe averate rate of x is 2. Using Poisson distribution, Calculate p(x = 1)?arrow_forwardA sample of manufactured items will be selected from a large population in which 8 percent of the items are defective. Of the following, which is the least value for a sample size that will allow for the sampling distribution of the sample proportion to be assumed approximately normal?arrow_forward
- In an Omani factory, a machine that produces "W-product" has been set so that the true average diameter of the "W-product" it produces is 0.602 in. If its diameter is within 0.04 in. of this target value, this is acceptable. Suppose, however, that the setting has changed during the course of production, so that the products have normally distributed diameters with mean value 0.601 in. and standard deviation 0.002 in. What percentage of the "W-product" produced will not be acceptablearrow_forwardThe inside diameter of a sample of 200 pen bodies produced by one machine is estimated to be 0.502 cm and the mean standard deviation is estimated to be 0.502 cm and the mean standard deviation is about 0.005 cm; the distribution of these diameters diameters is supposed to follow a normal distribution. These parts must pass through a fully automated assembly line, but they can only be suitable for this suitable for this purpose if and only if their diameter is between 0.496 and 0.508 cm. (1) What percentage of the pen bodies should be considered defective? (2) How does this percentage change if a new machine is purchased that only accepts diameters between 0.498 and 0.510 cm?arrow_forwardSuppose that n observations are chosen at random from a continuous pdf fY(y). What is the probability that the last observation recorded will be the smallest number in the sample?arrow_forward
- A simple random sample of size n =66, is obtained from a population that is skewed left with =33 and =3. . Does the population need to be normally distributed for the sampling distribution of x to be approximately normally distributed? Why? What is the sampling distribution of x? Does the population need to be normally distributed for the sampling distribution of x to be approximately normally distributed? Why?(A) Yes. The central limit theorem states that the sampling variability of nonnormal populations will increase as the sample size increases. (B) Yes. The central limit theorem states that only for underlying populations that are normal is the shape of the sampling distribution of x normal, regardless of the sample size, n. (C)No. The central limit theorem states that only if the shape of the underlying population is normal or uniform does the sampling distribution of x, become approximately normal as the sample size, n, increases. (D) No. The central limit theorem…arrow_forwardShow that a gamma distribution with α > 1 has a rel-ative maximum at x = β(α − 1). What happens when 0 <α< 1 and when α = 1?arrow_forwardThe absolute viscosity for sunflower oil is supposed to average 0.0311 Pa⋅s at 38 ∘C. Suppose a food scientist collects a random sample of 4 quantities of sunflower oil and computes the mean viscosity for his sample to be x¯=0.0318 Pa⋅s at 38 ∘C. Assume that measurement errors are normally distributed and that the population standard deviation of sunflower oil viscosity is known to be σ=0.0009 Pa⋅s. The scientist will use a one‑sample z‑test for a mean, at a significance level of α=0.01, to evaluate the null hypothesis, H0:μ=0.0311 Pa⋅s against the alternative hypothesis, H1:μ≠0.0311 Pa⋅s. Complete the scientist's analysis by calculating the value of the one-sample z‑statistic, the p‑value, and then deciding whether to reject the null hypothesis. First, compute the z‑statistic, z. Provide your answer precise to two decimal places. Avoid rounding within calculations. z= Determine the P-value of the test using either a table of standard normal critical values or…arrow_forward
- According to a random sample taken at 12 A.M., body temperatures of healthy adults have a bell-shaped distribution with a mean of 98.12°F and a standard deviation of 0.65°F. Using Chebyshev's theorem, what do we know about the percentage of healthy adults with body temperatures that are within 3 standard deviations of the mean? What are the minimum and maximum possible body temperatures that are within 3 standard deviations of the mean?arrow_forwardAccording to a random sample taken at 12 A.M., body temperatures of healthy adults have a bell-shaped distribution with amean of 98.26 F and a standard deviation of F. Using Chebyshev's theorem, what do we know about the percentageof healthy adults with body temperatures that are within 3 standard deviations of the mean? What are the minimum andmaximum possible body temperatures that are within 3 standard deviations of the mean?arrow_forwardThe distribution of weights (in pounds) of male students at a college is approximatelynormal with an unknown mean u and with an approximate standard deviation x = 15.3 lb. Considerrandom samples of 16 male students and let X denote the variable for the average weights of randomsamples of 16 male students.(a) What is the standard error of X with samples of size 16?(b) What is the distribution of X with samples of size 16?(c) Determine the minimum sample size n to ensure that the margin of error, E, of a two-sidedconfidence interval for u is at most 5 lb at 95% level of confidence.arrow_forward
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