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 2* = 1.960 0.99 2.576 402294.2602416.qx3zqy7 Jump to level 1 In a poll of 1000 randomly selected voters in a local election, 816 voters were in favor of fire department bond measures. What is the sample proportion p? Ex: 0.123 What is the margin of error m for the 90% confidence level? Ex: 0.123