Learn how to use a z-score table. Practice Problems for Z-Scores. Calculate the z-scores for the following: Sample Questions. Scores on a psychological well-being scale range from 1 to 10, with an average score of 6 and a standard deviation of 2. What is the z-score for a person who scored 4?A z-table, also called standard normal table, is a table used to find the percentage of values below a given z-score in a standard normal distribution. A z-score, also known as standard score, indicates how many standard deviations away a data point is above (or below) the mean. How to Read The Z Table. To map a Z score across a Z Table, it goes without saying that the first thing you need is the Z Score itself. In the above example, we derive that Eric's Z-score is 0.56. Once you have the Z Score, the next step is choosing between the two tables. Use a z-table to find probabilities corresponding to ranges of z-scores and to find p-values for z-tests. The z-table is divided into two sections, negative and positive z-scores. Negative z-scores are below the mean, while positive z-scores are above the mean.
To use the z-score table, start on the left side of the table and go down to 1.2. At the top of the table, go to 0.05. This corresponds to the value of 1.2 + .05 = 1.25. The value in the table is .8944 which is the probability. Roughly 89.44 percent of people scored worse than Zoe on the ACT.
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