Example 2: A previous study shows that the average age of employed students in a city is 19 years. A civic group made a recent survey on the age of employed students working in the same locality. A random sample of 20 respondents showed an average age of 20.4 years with a standard deviation of 2.14 years. Using a significance level of 0.05, has the average age of employed students gone higher? Solution: Step 1: Formulate the null and alternative hypotheses. Ho: 19 Ho: > 19 Step 2: Determine the level of significance. It is given that = 0.05.