Question 1043436
The CI for each is of the form z*sqrt {(p)(1-p)/n}, and that is added/subtracted to the point estimate
For A
2.576*sqrt (0.68)(0.32/2566; the sqrt term is 0.0092, and the product is 0.024
The CI is (0.656,0.704)
==================
B has a smaller number, a higher probability, but n is a lot less, so expect a slightly larger CI
2.576*sqrt(0.86)(0.14)/1128; sqrt term is 0.0103, and the product is 0.0266
(0.833,0.886)
==================
C has about the same number as B and a probability further from 50%, which will tend to lower the CI.
2.576*sqrt{(0.93)(0.07)/1085}; sqrt term is 0.0077, and the product is 0.020
(0.910,0.950)
==========
Can use calculator STAT then TESTS, then 1-prop z-interval
You need the number for each, and 68% of A is 1745, 86% of B is 970 and 93% of C is 1009.  These can be entered and the CI of 0.99 will be computed.