In an experiment to study the dependence of hypertension on smoking

  

In an experiment to study the dependence of hypertension on smoking habits, the following data were taken on 180 individuals:
Non-smokers Moderate Smokers Heavy Smokers
Hypertension 21 36 30
No hypertension 48 26 19
Test the hypothesis that the presence or absence of hypertension is independent of smoking habits. Use a 0.05 level of significance.