Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.2.
a. If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 9 pins is at least 51?
b. Without assuming population normality, what is the (approximate) probability that the sample mean hardness for a random sample of 40 pins is at least 51?
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Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.2
Rockwell hardness of pins of a certain type is known to have a mean value of...
Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.2. (Round your answers to four decimal places.) (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 11 pins is at least 51? (b) What is the (approximate) probability that the sample mean hardness for a random sample of 43 pins is at least 51?
Rockwell hardness of pins of a certain type is known to have a mean value of...
Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.6. (Round your answers to four decimal places.) (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51? (b) What is the (approximate) probability that the sample mean hardness for a random sample of 37 pins is at least 517
3. -/33.34 points DevoreStat9 5.E.053. My Notes Ask Your Rockwell hardness of pins of a certain...
3. -/33.34 points DevoreStat9 5.E.053. My Notes Ask Your Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.8. (Round your answers to four decimal places.) (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 13 pins is at least 51? 0.0212 (b) What is the approximate) probability that the sample mean hardness for a random...
5. -12 points DevoreStat9 5.E.053. My Notes Ask Your Teacher Rockwell hardness of pins of a...
5. -12 points DevoreStat9 5.E.053. My Notes Ask Your Teacher Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.5. (Round your answers to four decimal places.) (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 9 pins is at least 51? (b) What is the (approximate) probability that the sample mean hardness for a random...
A random sample of 12 shearing pins is taken in a study of the Rockwell hardness...
A random sample of 12 shearing pins is taken in a study of the Rockwell hardness of the head on the pin. Measurements on the Rockwell hardness were made for each of the 12, yielding an average value of 48.5. Assuming the population standard deviation is 1.5, construct a 90% confidence interval for the mean Rockwell hardness. Test the hypothesis that the average Rockwell hardness is 48 at a 0.01 level of significance.
5· The hardness of a certain alloy (measured on the Rockwell scale) is a random variable...
5· The hardness of a certain alloy (measured on the Rockwell scale) is a random variable X. Assume that this hardness is normally distributed with true standard deviation ơ-0.75. A sample of 20 alloys was taken and the average hardness was found to be 4.85 Compute a 95% confidence interval for the true hardness of this certain alloy. What sample size is necessary to estimate true average hardness within 0.2 with 90% confidence? b.
Suppose the Rockwell hardness of a particular alloy is normally distributed with mean 71 and standard deviation 3.
The Rockwell hardness of a metal is determined by impressing a hardened point into the surface of the metal and then measuring the depth of penetration of the point. Suppose the Rockwell hardness of a particular alloy is normally distributed with mean 71 and standard deviation 3. (a) If a specimen is acceptable only if its hardness is between 70 and 74, what is the probability that a randomly chosen specimen has an acceptable hardness? (Round your answer to four decimal...
Suppose the Rockwell hardness of a particular alloy is normally distributed with mean 69 and standard deviation 3.
The Rockwell hardness of a metal is determined by impressing a hardened point into the surface of the metal and then measuring the depth of penetration of the point. Suppose the Rockwell hardness of a particular alloy is normally distributed with mean 69 and standard deviation 3. (a) If a specimen is acceptable only if its hardness is between 68 and 73, what is the probability that a randomly chosen specimen has an acceptable hardness? (Round your answer to four decimal...
If selecting samples of size n≤30 from a population with a known mean and standard deviation,...
If selecting samples of size n≤30 from a population with a known mean and standard deviation, what requirement, if any, must be satisfied in order to assume that the distribution of the sample means is a normal distribution? A) The population must have a normal distribution. B) The population must have a mean of 1. C) The population must have a standard deviation of 1. D) None; the distribution of sample means will be approximately normal.
Questions 23-30: A normal population has a mean μ = 50 and a standard deviation σ...
Questions 23-30: A normal population has a mean μ = 50 and a standard deviation σ = 8. That is, ?~?(50,8). Circle your final answer for each question below. 23. What is the z-score for an individual with a value of 38? 24. What is the probability that a randomly chosen individual from this population will be greater than 40? 25. What is the probability that a randomly chosen individual from this population will be between 44 and 60? 26....
Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.6. (Round your answers to four decimal places.) (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51? (b) What is the (approximate) probability that the sample mean hardness for a random sample of 37 pins is at least 517
3. -/33.34 points DevoreStat9 5.E.053. My Notes Ask Your Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.8. (Round your answers to four decimal places.) (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 13 pins is at least 51? 0.0212 (b) What is the approximate) probability that the sample mean hardness for a random...
5. -12 points DevoreStat9 5.E.053. My Notes Ask Your Teacher Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.5. (Round your answers to four decimal places.) (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 9 pins is at least 51? (b) What is the (approximate) probability that the sample mean hardness for a random...
5· The hardness of a certain alloy (measured on the Rockwell scale) is a random variable X. Assume that this hardness is normally distributed with true standard deviation ơ-0.75. A sample of 20 alloys was taken and the average hardness was found to be 4.85 Compute a 95% confidence interval for the true hardness of this certain alloy. What sample size is necessary to estimate true average hardness within 0.2 with 90% confidence? b.
The Rockwell hardness of a metal is determined by impressing a hardened point into the surface of the metal and then measuring the depth of penetration of the point. Suppose the Rockwell hardness of a particular alloy is normally distributed with mean 71 and standard deviation 3. (a) If a specimen is acceptable only if its hardness is between 70 and 74, what is the probability that a randomly chosen specimen has an acceptable hardness? (Round your answer to four decimal...
The Rockwell hardness of a metal is determined by impressing a hardened point into the surface of the metal and then measuring the depth of penetration of the point. Suppose the Rockwell hardness of a particular alloy is normally distributed with mean 69 and standard deviation 3. (a) If a specimen is acceptable only if its hardness is between 68 and 73, what is the probability that a randomly chosen specimen has an acceptable hardness? (Round your answer to four decimal...
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