How do you find the z score of a percentile?
For ex.: Find the z score of P88
To find the z-score of a percentile, you can use the standard normal distribution table or a calculator that can perform normal distribution calculations.
Here's how you can find the z-score for a given percentile, like P88 (88th percentile):
Step 1: Identify the area to the left of the percentile. In this case, for P88, the area to the left is 0.88.
Step 2: Use the standard normal distribution table or calculator to determine the z-score associated with the area to the left.
If using a standard normal distribution table:
- Look up the corresponding value in the table for an area of 0.88. In this case, it would be around 1.17.
- The positive and negative z-scores correspond to the same area under the curve, so to find the z-score for an area of 0.88, you can assume the z-score will be positive.
If using a normal distribution calculator:
- Input the area to the left (0.88) into the calculator and find the corresponding z-score.
So, the z-score for P88 is approximately 1.17.
try playing around here, to see how all that Z table stuff works:
http://davidmlane.com/hyperstat/z_table.html