NarStor, a computer disk drive manufacturer, claims that the average time to failure for its hard drives is 14,400 hours. You work for a consumer group that has decided to examine this claim. Technicians ran 16 drives continuously for three years. Recently the last drive failed. The time to failure (in hours) are given below. Time Until Failure(Hours) 330 620 1870 2410 4620 6396 7822 8102 8309 12,882 14,419 16,092 18,384 20,916 23,812 25,814 Conduct a hypothesis test to determine whether there is any evidence that the average time to failure is less than the manufacturer’s claim. Use alpha = 0.01 What assumption did you make in performing the test? What is the p-value?
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
- NarStor, a computer disk drive manufacturer, claims that the average time to failure for its hard drives is 14,400 hours. You work for a consumer group that has decided to examine this claim. Technicians ran 16 drives continuously for three years. Recently the last drive failed. The time to failure (in hours) are given below.
|
Time Until Failure(Hours) |
|||||||
|
330 |
620 |
1870 |
2410 |
4620 |
6396 |
7822 |
8102 |
|
8309 |
12,882 |
14,419 |
16,092 |
18,384 |
20,916 |
23,812 |
25,814 |
- Conduct a hypothesis test to determine whether there is any evidence that the average time to failure is less than the manufacturer’s claim. Use alpha = 0.01
- What assumption did you make in performing the test?
- What is the p-value?
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