The confidence level would be 99.5%.
When we know the confidence level, we find the z-score by:
Dividing the CL by 100;
Subtracting this result from 1;
Dividing this result by 1;
Subtracting this result by 1.
Algebraically, this looks like:
Using a z-table (http://www.z-table.com), we see that a z-score of 2.81 results in an area under the curve of 0.9975, so we now have
To begin solving this, we will subtract 1 from both sides:
We will now multiply both sides by 2:
Subtract 1 from both sides:
Multiply both sides by 100:
CL = 99.5
When we know the confidence level, we find the z-score by:
Dividing the CL by 100;
Subtracting this result from 1;
Dividing this result by 1;
Subtracting this result by 1.
Algebraically, this looks like:
Using a z-table (http://www.z-table.com), we see that a z-score of 2.81 results in an area under the curve of 0.9975, so we now have
To begin solving this, we will subtract 1 from both sides:
We will now multiply both sides by 2:
Subtract 1 from both sides:
Multiply both sides by 100:
CL = 99.5