The thickness (in millimeters) of the coating applied to hard drives is one characteristic that determines the usefulness of the product. When no unusual circumstances are present, the thickness (x) has a normal distribution with a mean of 4 mm and a standard deviation of 0.03 mm. Suppose that the process will be monitored by selecting a random sample of 25 drives from each shift's production and determining x, the mean coating thickness for the sample. LUSE SALT (a) Describe the sampling distribution of x for a random sample of size 25. The distribution of x is ---Select-- ✓with mean 4 -20% = 4 + 20 = mm and standard deviation (b) When no unusual circumstances are present, we expect x to be within 20 of 4 mm, the desired value. An x value farther from 4 mm than 20 is interpreted as an indication of a problem that needs attention. Calculate 4 ± 20% mm mm mm. (c) Referring to part (b), what is the probability that a sample mean will be outside 4 + 20- just by chance (that is, when there are no unusual circumstances)? (Round your answer to four decimal places.)

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
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Chapter10: Statistics
Section10.6: Summarizing Categorical Data
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The thickness (in millimeters) of the coating applied to hard drives is one characteristic that determines the usefulness of the product. When no unusual circumstances are present, the thickness (x) has a normal
distribution with a mean of 4 mm and a standard deviation of 0.03 mm. Suppose that the process will be monitored by selecting a random sample of 25 drives from each shift's production and determining x, the
mean coating thickness for the sample.
USE SALT
(a) Describe the sampling distribution of x for a random sample of size 25.
The distribution of x is ---Select--
✓with mean
4- 20x =
4 + 20 =
(b) When no unusual circumstances are present, we expect x to be within 20 of 4 mm, the desired value. An x value farther from 4 mm than 20 is interpreted as an indication of a problem that needs
attention. Calculate 4 ± 20x
mm
mm and standard deviation
mm
mm.
(c) Referring to part (b), what is the probability that a sample mean will be outside 4 ± 20 just by chance (that is, when there are no unusual circumstances)? (Round your answer to four decimal places.)
(d) Suppose that a machine used to apply the coating is out of adjustment, resulting in a mean coating thickness of 4.03 mm. What is the probability that a problem will be detected when the next sample is
taken? (Hint: This will occur if x > 4 + 20 orx < 4-20 when μ = 4.03. Round your answer to four decimal places.)
Transcribed Image Text:The thickness (in millimeters) of the coating applied to hard drives is one characteristic that determines the usefulness of the product. When no unusual circumstances are present, the thickness (x) has a normal distribution with a mean of 4 mm and a standard deviation of 0.03 mm. Suppose that the process will be monitored by selecting a random sample of 25 drives from each shift's production and determining x, the mean coating thickness for the sample. USE SALT (a) Describe the sampling distribution of x for a random sample of size 25. The distribution of x is ---Select-- ✓with mean 4- 20x = 4 + 20 = (b) When no unusual circumstances are present, we expect x to be within 20 of 4 mm, the desired value. An x value farther from 4 mm than 20 is interpreted as an indication of a problem that needs attention. Calculate 4 ± 20x mm mm and standard deviation mm mm. (c) Referring to part (b), what is the probability that a sample mean will be outside 4 ± 20 just by chance (that is, when there are no unusual circumstances)? (Round your answer to four decimal places.) (d) Suppose that a machine used to apply the coating is out of adjustment, resulting in a mean coating thickness of 4.03 mm. What is the probability that a problem will be detected when the next sample is taken? (Hint: This will occur if x > 4 + 20 orx < 4-20 when μ = 4.03. Round your answer to four decimal places.)
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