Question 1118456
80% CI is +/-1.28sqrt(p*(1-p)/n)
half-interval is +/-0.06
0.06=1.28sqrt(p*(1-p)/n)
0.0036=1.64*p(1-p)/n, squaring both sides
0.0036n=1.64*0.33*0.67
n=0.36/0.0036
n=100

Use 0.5 for p, if no estimate there.
0.0036=1.64*0.25/n, after squaring
0.0036n=0.41
n=113.88 or 114.