The service life of a battery used in a cardiac pacemaker assumed to be normally
ID: 3206688 • Letter: T
Question
The service life of a battery used in a cardiac pacemaker assumed to be normally distributed. A random sample of ten batteries is subjected to an accelerated life test by running them continuously at an elevated temperature until failure and the following lifetimes (in hours) are obtained: 25.5, 26.1, 26.8, 23.2, 24.2, 28.4, 25.0, 27.8, 27.3 and 25.7. The manufacturer wants to be certain that the mean battery life exceeds 25h. What conclusions can be drawn from the data (use a = 0.05)? Construct a 90% two-sided confidence interval on mean life in the accelerated test. Construct a normal probability plot of the battery life data. What conclusions can you draw?Explanation / Answer
Solution:
a. For sample t-test ,
It will be testing for greater than hypothesized mean.
By calculating,we get the P-value = 0.042.
It can reject the null hypothesis ,so that the mean is 25 for the alternative of mean > 25.
b. For sample t-test.
It will be testing for greater than hypothesized mean.
If Confidence internal of 90 is not equal.
we get the values= (25.058, 26.942)
C. The plotted points fall approx. along the straight line, so the assumption of that battery life is normally distributed is appropriate.