Posted by Lisa on .
You are studying the rate of incidence of skin cancer in people who live near the equator. Your survey of 200 people from the area has shown that 7 of them developed skin cancer.
Provide a 99% confidence interval for the true rate of incidence.

statistics 
MathGuru,
Example of a proportional confidence interval formula:
CI99 = p + or  (2.58)[√(pq/n)]
...where p = x/n, q = 1  p, and n = sample size.
Note: + or  2.58 represents 99% confidence interval.
For p in your problem: 7/200 = .035
For q: 1  p = 1  .035 = .965
n = 200
I let you take it from here to calculate the interval.