Construct a 95% CI for the 5-year true rate of cataracts among the excessive-sunlight-exposure group? The researchers

Question:

Construct a 95% CI for the 5-year true rate of cataracts among the excessive-sunlight-exposure group?

The researchers decide to extend the study to a 5-year period and find that 20 of the 200 people develop a cataract over a 5-year period. Suppose the expected incidence of cataracts among 65- to 69-year-olds in the general population is 5% over a 5-year period.