Answer to Question #40819 in Programming & Computer Science for Sumendra

Question

Suppose a regional computer centre A wants to evaluate the performance of its disk memory
system. One measure of performance is the average time between failures of its disk drive.
To estimate this value, the centre recorded the time between failures for a random sample of
45 disk-drive failures. The following sample statistics were computed:

BAR x =1768 hours, s = 213 hours

iii. How large a sample would have been required to achieve 99% confidence interval that
the margin of error of estimate would be 20? [1.5 marks]

iv. Another sample of 50 disk-drive failures has been recorded from another computer centre B. The mean that obtained is 1720 with standard deviation 218. Estimate the difference
of the true mean time failures with a 90% confidence interval. [3 marks]