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 2* = 1.960 0.99 2* = 2.576 V Jump to level 1 1 V A poll for a statewide election has a margin of error of 3.07 percentage points. 2 V How many voters should be sampled for a 95% confidence interval? Round up 3 to the nearest whole number. A Ex: 1234 voters 2 3 4 Check Next Feedback