Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.4. (Round youranswers to four decimal places.)A USE SALT(a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 14 pins isat least 51?(b) What is the (approximate) probability that the sample mean hardness for a random sample of 41 pins is at least 51?You may need to use the appropriate table in the Appendix of Tables to answer this question.

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A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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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 1.5. (Round your answers to four decimal places.) n USE SALT (a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 14 pins is at least 51? 0.6667 (b) What is the (approximate) probability that the sample mean hardness for a random sample of 39 pins is at least 51?
Q3
3. The thickness of a road is nommally distribuned with standard deviation 5.8 cm. A random sample of 15 roads were taken If the probability that the sample mean road thickness is at least 10.2 cm is K2, whut is the average thickness of all the roads
': Consider a puzzle is created where the amount of time it takes an individual to solve the puzzle follows a normal distribution with a standard deviation of 2 minutes. a) If a sample of 13 individuals was collected, what is the probability the sample mean time required to solve the puzzle would be within 1.2 minutes of the population mean? b) What would the required sample size be if we wanted the sample mean to be within half a minute of the population mean with a probability of .9?
The amount of pollutants that are found in waterways near large cities is normally distributed with mean 8.7 ppm and standard deviation 1.7 ppm. 18 randomly selected large cities are studied. Round all answers to 4 decimal places where possible. a. What is the distribution of X? X N( b. What is the distribution of T? I - N( c. What is the probability that one randomly selected city's waterway will have more than 8.9 ppm pollutants?
The scores of students in a diagnostic test administered in an introductory course in statistics are normally distributed with a mean of 60 points and a standard deviation of 4 points. A random sample of 25 students is selected. Answer the following questions below: Prompts Submitted Answers What is the value of the standard error? Choose a match What is the value of z? Choose a match What is the probability that the random Choose a match sample of 25 students will have a mean score below 59 points?
Suppose that the mean and standard deviation of plants height are 130 and 32, respectively, if a random sample of size 49 is slected from these plants, then the probability that their average height is more than 125 is closest to: O a. 0.20 O b.0.86 Oc. 0.26 O d. 0.14 O e. 0.74 Next page
THE ANSWER IS NOT 2.02!!!!
A random variable X is normally distributed. It has a mean of 232 and a standard deviation of 25. Label the following with the correct symbols from the drop-down box: ? = 232 ? = 25 a) If you take a sample of size 10, can you say what the shape of the sampling distribution for the sample mean is? ? Why or why not? Check what must apply. n is less than 30 distribution of population is normal n is at least 30 distribution of population is not normal b) For a sample of size 10, state the mean and the standard deviation of the sampling distribution of the sample mean. mean of the sampling distribution of the sample mean when n = 10: standard deviation of the sampling distribution of the sample mean when n = 10: Round your final answer to two decimal places.
Questions A and C. Please!
Ch6. "A carpet manufacturing company is comparing the tensile strengths of two different types of synthetic fiber. Synthetic fiber A used in manufacturing carpet has tensile strength that is normally distributed with mean 75 psi and standard deviation 12 psi, and synthetic fiber B has tensile strength that is 70 psi and standard deviation 12 psi. Random sample of nA = 16 and nB = 9 of fiber specimens are selected. Find the probability that the sample mean of fiber specimen A exceeds the sample mean of fiber specimen B by 4."
A random sample of 28 MBAs working in New York revealed that their mean annual salary was $123,000. Suppose that the population standard deviation σ is $22,000 but that the population mean µ is unknown. What is the point estimate (i.e. the "best guess") of the mean salary µ of all MBAs in this city?

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