Questions: Find the critical value (zc) necessary to form a confidence interval at the level of confidence shown below.
(c=0.97)
(zc=)
(Round to two decimal places as needed.)
Transcript text: Find the critical value $z_{c}$ necessary to form a confidence interval at the level of confidence shown below.
\[
c=0.97
\]
\[
z_{c}=
\]
$\square$
(Round to two decimal places as needed.)
Solution
Find the critical value \( z_{c} \) for a confidence level of \( c = 0.97 \).
Step 1: Determine the tail area.
For a confidence level of \( c = 0.97 \), the area in the tails is \( 1 - c = 1 - 0.97 = 0.03 \). Since the normal distribution is symmetric, each tail will have an area of \( \frac{0.03}{2} = 0.015 \).
Step 2: Find the z-score corresponding to the tail area.
Using the standard normal distribution table or a calculator, find the z-score that corresponds to a cumulative probability of \( 1 - 0.015 = 0.985 \). This z-score is approximately \( 2.17 \).
Step 3: Round the z-score to two decimal places.
The z-score \( 2.17 \) is already rounded to two decimal places.