Question: We randomly selected 100 displays and measured their lifetime in hours (in thousands). Our results are included in the following table:

Assume that the lifetime is a random variable \(X\tilde{\ }N\left( \mu ,{{\sigma }^{2}} \right)\).

a) Find a 95% confidence interval for the population mean of display lifetime!

b) Find the maximal population mean display lifetime with 95% confidence!

c) Find the minimal population mean display lifetime with 90% confidence!

d) Do the same for \({{\sigma }^{2}}\)