Question 1043430
99% CI is z*sqrt{ p*(1-p)/n}
z=2.576
p=1415/3095=0.4572
1-p=0.5428
sqrt of {0.4572*0.5428/3095}=0.00895
multiply that by 2.576 to get the interval width on each side of the point estimate, which is 0.4572.
0.023067
(0.434,0.480)
We don't know the true proportion who stated they have started paying bills online in the last year, but we are extremely confident, 99% so, that the true number lies in the above interval.