Electronic devices contain electric circuits etched into wafers made of silicon. These silicon wafers are sealed with an ultrathin layer of silicon dioxide, in a process known as oxidation. This can be done with either new or recycled wafers.
In a study described in the book Statistical Case Studies for Industrial Process Improvement by V. Czitrom and P. Spagon, both new and recycled wafers were oxidized, and the thicknesses of the layers were measured to determine whether they tended to differ between the two types of wafers. Recycled wafers are cheaper than new wafer, so the hope was that they would perform at least as well as the new wafers. Following are 36 thickness measurements (in tenth s of a nanometer) for both new and recycled wafers.
Suppose that it is desired to use the type of wafer whose distribution has less spread. Write a brief paragraph that explains which type of wafer to use and why. Which measure is more useful for spread in this case, the standard deviation or the
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Elementary Statistics ( 3rd International Edition ) Isbn:9781260092561
- Lichen has a high absorbance capacity for radiation fallout from nuclear accidents. Since lichen is a major source for Alaskan caribou, and caribou is major food source tor the Alaskan villagers, it is important to monitor the level of radioactivity in lichen. Researcher at the University of Alaska, Fairbanks, collected 9 lichen specimens and measured the amount in micro-curies per milliliter) of the radioactive element cesium-137 for each. Using the Minitab software, it was found that the mean and standard deviation for the 9 observations were X = 0.009027 аnd s = 0.004854 A) Give a point estimate for the mean amount of cesium in lichen specimens collected in Alaska. B) Give the t- value used in a small sample 95% confidence interval for the true mean amount of cesium in Alaskan lichen specimens. C) Form a 95% confidence interval for the true mean amount of cesium in Alaskan lichen specimens. D) Give a practical interpretation for the interval you obtained in part C. E) What…arrow_forwardThe DENR has a new procedure to detect algal bloom in water being tested. This new procedure is important because, it could be used to detect three different contaminants-organic pollutants, volatile solvents, and chlorinated compounds. The department claims that it can detect high levels of organic pollutants with 99.95% accuracy, volatile solvents with 89.70% accuracy, and chlorinated compounds with 99.70% accuracy. If an algal bloom is not present, the test does not signal. Samples are prepared for the calibration of the test and 60% of them are contaminated with organic pollutants, 27% with volatile solvents, and 13% with traces of chlorinated compounds. A test sample is selected randomly. Denote as follows: S = signal, O = organic pollutants, V = volatile solvents, C = chlorinated compounds. If the test signals, what is the probability that chlorinated compounds are present? (Show complete solution in your answer sheet) O a. P(CIS) = 0.1386 Ob.P(C|S) = 0.1184 OC. None among the…arrow_forwardA sociologist wants to determine if the life expectancy of people in Africa is less than the life expectancy of people in Asia. The data obtained is shown in the table below. Africa Asia = 63.3 yr. 1 X,=65.2 yr. 2 o, = 9.1 yr. = 7.3 yr. n1 = 120 = 150arrow_forward
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