7. In an attempt to demonstrate if there is any link between exposure to asbestos (A) and pulmonary fibrosis (F), the medical records of 100 welders were examined.

67 welders were exposed to asbestos 11 welders were exposed to asbestos but did not develop pulmonary fibrosis 4 welders developed pulmonary fibrosis but were not exposed to asbestos

a) Calculate the percent (rounded to 1 decimal place) of welders exposed to asbestos that had pulmonary fibrosis. (1 mark)

b) Calculate the percent (rounded to 1 decimal place) of welders not exposed to asbestos that had pulmonary fibrosis. (1 mark)

c) Calculate the correlation value and justify (explain) whether or not there seems to be a statistically significant link between being exposed to asbestos and developing pulmonary fibrosis. (3 marks)