In: Statistics and Probability
A random sample of n = 15 heat pumps of a certain type yielded the following observations on lifetime (in years):
2.0 | 1.4 | 6.0 | 1.8 | 5.3 | 0.4 | 1.0 | 5.3 |
15.9 | 0.8 | 4.8 | 0.9 | 12.1 | 5.3 | 0.6 |
(a) Assume that the lifetime distribution is exponential and use an argument parallel to that of this example to obtain a 95% CI for expected (true average) lifetime. (Round your answers to two decimal places.)
,
years
(b) How should the interval of part (a) be altered to achieve a
confidence level of 99%?
A 99% confidence level requires using a new value of n to capture an area of 0.005 in each tail of the chi-squared distribution.A 99% confidence level requires using critical values that capture an area of 0.1 in each tail of the chi-squared distribution. A 99% confidence level requires using critical values that capture an area of 0.005 in each tail of the chi-squared distribution.A 99% confidence level requires using a new value of n to capture an area of 0.1 in each tail of the chi-squared distribution.
(c) What is a 95% CI for the standard deviation of the lifetime
distribution? [Hint: What is the standard deviation of an
exponential random variable?] (Round your answers to two decimal
places.)
,
years