Question

Find tα/2 for n = 18 and a 99% confidence interval.

Answer 1

Answer:

2.576

Step #5: Find the Z value for the selected confidence interval.

Confidence Interval Z

85% 1.440

90% 1.645

95% 1.960

99% 2.576

With a 95 percent confidence interval, you have a 5 percent chance of being wrong. ... A 99 percent confidence interval would be wider than a 95 percent confidence interval (for example, plus or minus 4.5 percent instead of 3.5 percent).

tα/2

• Notation: – E = the margin of error – tα/2 = the critical value of z. – s is the sample standard deviation – n is the sample size – α = 1 − confidence level (in decimal form) ∗ If the confidence level is 90% then α = 1 − .