A company advertises a population mean battery standby time of 235 hours. A manager believes the population mean is less than 235 hours. A random sample gives n=200n=200n=200, ∑x=46313\sum x=46313∑x=46313 and ∑x2=10861255\sum x^2=10861255∑x2=10861255.
Calculate the sample mean and sample standard deviation.
Using the sample standard deviation as an estimate of the population standard deviation, test the manager's belief at the 1% significance level.