A plant manager takes a random sample of 100% sick days and finds that 30% of the plant labor force in the 20 to 29 age group took 26 of the sick days, that 40% of the labor force in the 30 to 39 age group took 37 sick days, that 20% in the 40 to 49 age group took 24 sick days, and that 10% of the 50-andover age group took 13 sick days. How can the manager test at the 5% level of significance the hypothesis that age is not a factor in taking sick days?