How many tissues should a package of tissues contain? Researchers determined that 68 tissues is the avg. number of tissues used during a cold. Suppose a random sample of 100 tissues users yielded the following data o the number of tissues used during a cold:
x-bar = 63, s = 17
Suppose the alternative we wanted to test was Ha: µ < 68. State the correct rejection region for α = .05.
Solution: The alternative hypothesis tells us that we have a left-tailed test. For a 0.05 significance level, we have that the critical value is -1.96. The critical region is then
In our example, the z-statistics is computed as
That means that we reject the null hypothesis and accept the alternative.