The manufacturer of a certain brand of automobiles component claims that mean life of these component is 70 months. An independent agency wants to check this claim and took a randor sample of 40 components and found that the mean life for this sample is 67 months with a standard deviation of 5 months. At 5% LOS, can we conclude that the mean life of these component is less than 70 months?

The manufacturer of a certain brand of automobiles component claims that mean life of these component is 70 months. An independent agency wants to check this claim and took a randor sample of 40 components and found that the mean life for this sample is 67 months with a standard deviation of 5 months. At 5% LOS, can we conclude that the mean life of these component is less than 70 months?

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...

See similar textbooks

Similar questions

Ann thinks that there is a difference in quality of life between rural and urban living. She collects information from obituaries in newspapers from urban and rural towns in Idaho to see if there is a difference in life expectancy. A sample of 3 people from rural towns give a life expectancy of xr¯=79��¯=79 years with a standard deviation of sr=7.57��=7.57 years. A sample of 14 people from larger towns give xu¯=82��¯=82 years and su=5.48��=5.48 years. Does this provide evidence that people living in rural Idaho communities have different life expectancy than those in more urban communities? Use a 5% level of significance. (a) State the null and alternative hypotheses: (Type ‘‘mu_r′′‘‘��_�″ for the symbol μr�� , e.g. mu_rnot=mu_u��_��=��_� for the means are not equal, mu_r>mu_u��_�>��_� for the rural mean is larger, mu_r<mu_u��_�<��_� , for the rural mean is smaller. )H0�0 = equation editor Equation Editor Ha�� = equation editor Equation Editor (b) The degree of…
The antibody production of 12 male red-winged blackbirds before and after receiving testosterone implants was compared. The units for antibody levels were natural log (10-3 optical density) per minute (In(mOD/min)). The mean change in antibody production was d = 0.056, and the standard deviation was sd = 0.225 If you were assigned the task of repeating this experiment, and wanted to ensure that you could detect a mean change of 0.02 units with a probability of 0.8, then what sample size would you use? Since we are calculating n for a study of individuals, answers should be rounded up to the next whole number.
A manufacturer of bolts has a quality-control policy that requires it to destroy any bolts that are more than 2 standard deviations from the mean. The quality-control engineer knows that the bolts coming off the assembly line have mean length of 9cm with a standard deviation of 0.05cm. For what lengths will a bolt be�� destroyed?
The scores on a standardized test are normally distributed with a mean of 95 and standard deviation of 25. What test score is 0.3 standard deviations below the mean?
The scores on a standardized test are normally distributed with a mean of 120 and standard deviation of 5. What test score is 1.1 standard deviations above the mean?
Samples of emissions from three suppliers are classified for conformance to air-quality specifications. The results from 100 samples are summarized as follows: Conforms Yes No 1 22 8 Supplier 2 25 5 3 30 10 Let A denote the event that a sample is from supplier 1, and let B denote the event that a sample conforms to specifications. (a) Are A and B independent events? Independent O Not independent (b) Determine P(B|A). Round your answer to two decimal places (e.g. 98.76).
The scores from the first exam of a pre-calculus class determined a mean of 73.5 and a standard deviation of 17.9. 1. Calculate an exam score that is 2 standard deviations below the mean. 2. Calculate an exam score that is 1 standard deviation above the mean.
The scores on a standardized test are normally distributed with a mean of 115 and standard deviation of 20. What test score is 2.2 standard deviations above the mean?
The sample mean of depression scores of 16 fifth graders was 4.4 with standard deviation of 8. If the population mean of this depression score is 6, what is the calculated t score for this sample?
The scores on a standardized test are normally distributed with a mean of 85 and standard deviation of 10. What test score is 1.7 standard deviations above the mean?
From generation to generation, the mean age when smokers first start to smoke varies. However, the standard deviation of the age when smokers first start to smoke remains constant at around 2.1 years. The American Lung Association claims that the mean age when smokers first start to smoke is at least 17. A survey of 40 randomly selected smokers of this generation was done and it was found that the mean age when smokers first started to smoke was 18.1. Is there enough evidence to reject the claim? Describe what a Type I error is for this situation. Describe what a Type II error is for this situation.
An advertising agency that serves a major radio station wants to estimate the mean amount of time that the station’s audience spends listening to the radio daily. From past studies, the standard deviation is estimated as 45 minutes. What sample size is needed if the agency wants to be 99% confident of being correct to within ±5 minutes?