Utilize the negative Z score table underneath to discover esteems on the left of the mean as can be found in the chart close by. Comparing esteems which are not exactly the mean are set apart with a negative score in the z-table and represent the territory under the chime bend to one side of z.

negative-z-table

Positive Z score table 

positive-z-score-chart 

Utilize the positive Z score table underneath to discover esteems on the privilege of the mean as can be found in the diagram close by. Relating values that are more noteworthy than the mean are set apart with a positive score in the z-table and represent the region under the chime bend to one side of z.

Positive-z-table

How to use the Z table

Give us a chance to see how to ascertain the Z-score and utilize the Z-table with a straightforward genuine model. 

300 understudy’s test scores are counted toward the finish of the semester. Eric scored 800 imprints (X) altogether out of 1000. The normal score for the bunch was 700 (µ) and the standard deviation was 180 (σ). We should discover how well Eric scored contrasted with his group mates. 

Utilizing the above information we have to initially institutionalize his score and utilize the particular z-table to decide how well he performed contrasted with his group mates. 

To fine out the Z score we utilize the equation 

Z score = ( x – µ )/σ 

Z score = (800-700)/150 

Z score = 0.56 

Since we have Eric’s Z score, we will utilize the Z-table to anticipate how fortunate or unfortunate Eric performed contrasted with his bunch mates. Since Eric’s Z score worth is certain, we will utilize the Z-table with positive qualities (Table 1.2). 

Locate the comparing an incentive for the initial two digits on the y pivot (0.5 dependent on Eric’s Z score). When you have that, go close by the X pivot to discover the incentive for the subsequent decimal (0.06 dependent on Eric’s Z score). We get the number 0.7123. To get this as a rate we increase that number with 100. In this manner 0..7123 x 100 = 71.23%. Consequently, we discover that Eric showed improvement over 71.23% of understudies. 

Why are there two Z tables?

There are two Z tables to make things less entangled. Sure it tends to be consolidated into one single bigger Z-table yet that can be somewhat overpowering for a ton of learners and it additionally expands the opportunity of human mistakes during estimations. Utilizing two Z tables makes life simpler with the end goal that depends on whether you need the know the territory from the mean for a positive worth or a negative worth, you can utilize the individual Z score table. 

In the event that you need to know the zone between the mean and a negative worth, you will utilize the main table (1.1) that appeared above which is the left-hand/negative Z-table. On the off chance that you need to know the zone between the mean and a positive worth, you will the subsequent table (1.2) above which is the right-hand/positive Z-table. 

What is Standard Deviation? (σ) 

Standard Deviation signified by the image (σ), the greek letter for sigma, is only the square base of the Difference. While Fluctuation is normal of the squared contrasts from the Mean.

Test Inquiries For Training 

1. What is P (Z ≥ 1.20) 

Answer: 0.11507 

To discover the appropriate response utilizing the above Z-table, we will initially take a gander at the relating an incentive for the initial two digits on the Y hub which is 1.2 and afterward go to the X hub for discovering the incentive for the second decimal which is 0.00. Subsequently, we get the score as 0.11507 

2. What is P (Z ≤ 1.20) 

(Same as above utilizing the other table. Have a go at illuminating this yourself for training)