Feedback? CHALLENGE ACTIVITY 4.8.1: 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* = 2.576 402216.1927122.qx3zqy7 Jump to level 1 v 1 V A poll for a statewide election has a margin of error of 1.65 percentage points. 2 V How many voters should be sampled for a 99% confidence interval? Round up 3 to the nearest whole number. Ex: 1234 $ voters 4 2 3 4 Check Next