7.2: Confidence intervals for population ... Challenge activities CHALLENGE ACTIVITY 7.2.1: Confidence intervals for population proportions. Critical values for quick reference during this activity. Confidence level Critical value 0.90 2* = 1.645 0.95 z* = 1.960 0.99 2* = 2.576 Jump to level 1 N - K In a poll of 1000 randomly selected voters in a local election, 699 voters were in favor of school bond measures. 3 What is the 99% confidence interval? [ Ex: 0.123@) Ex: 0.123 @ ] [smaller value, larger value]