In a forward direction use of the Z-Table, you’ll often. Start with a normal distribution with mean left.muright. and standard deviation left. To do this, we refer back to the standard normal distribution table. Using the z-score, 0.67, and the y-axis and x-axis of the standard normal distribution table, this guided us to the appropriate value, 0. In this case, we need to do the exact reverse to find our z-score. We saw how we can convert raw scores to z-scores then find the area under the curve which gives us the probabilities above, below and between values. To find out we work backwards. To find it we need to use an inverse normal table or the excel function NORMSINV(.98) and we get the z-score of 2.054.
Find the corresponding percentile for Z by looking in the body of the Z-table (see below) and finding the probability that is closest to p (from Step 1a) or 1 p (from Step 1b). Find the row and column this probability is in (using the table backwards). I’m having issues using the standard normal table backwards to look up the z value. For example, If a left tail area 0.2 how does z -0.84?. The values in the main table are probabilities that Z is between 0 and +a. What we have here is the reverse problem to those encountered so far.
Using the Table Backwards: Finding Z Example 5 (based on Example 5.10 in the book) Daily paint production at a manufacturing plant has a mean of 100,000 gals. We compute the z-scores using the sampling distribution. We have.
How To Find A Percentile For A Normal Distribution