Enter the mean, the total score, and the standard deviation into the Z Ratio Calculator. The calculator will evaluate and display the Z Ratio. 

Z Ratio Formula

The following formula is used to calculate the Z Ratio. 

ZR = (M-S) / SD

  • Where ZR is the Z Ratio ( )
  • M is the mean 
  • S is the total score 
  • SD is the standard deviation 

How to Calculate Z Ratio?

The following example problems outline how to calculate Z Ratio.

Example Problem #1

  1. First, determine the mean.
    • The mean is calculated to be : 5.
  2. Next, determine the total score. 
    • The total score is measured to be: 2.
  3. Next, determine the standard deviation. 
    • The standard deviation is found to be: 1.5.
  4. Finally, calculate the Z Ratio using the formula above: 

ZR = (M-S) / SD

The values given above are inserted into the equation below and the solution is calculated:

ZR = (5-2) / 1.5 = 2

Example Problem #2

The variables required for this problem are provided below:

mean = 6

total score = 4

standard deviation = 1.35

Test your knowledge using the equation and check your answer with the calculator above.

ZR = (M-S) / SD = ( )