A company held a blood pressure screening clinic for its employees. The results are summarized in the table below by age group and blood pressure level:

a) Find the marginal distribution of blood pressure level.
b) Find the conditional distribution of blood pressure level within each age group.
c) Compare these distributions with a segmented bar graph.
d) Write a brief description of the association between age and blood pressure among these employees.
e) Does this prove that people's blood pressure increases they age? Explain.