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How to Find Percentiles from Z-Score on TI-84

The Normal Cumulative Distribution Function normalcdf() is used to find percentiles from z score on the TI-84 calculator.

normalcdf

(lower bound, z-score, μ, σ)

where:

  • lower bound:  lower bound for the given z-score. We use infinity as lower bound.
  • Z-score : given z-score
  • μ: population mean
  • σ: population standard deviation

How to find percentile from z score usint TI 84

The following steps will guide us on how to calculate the Percentiles from Z-Score using TI-84 Calculator:

Step 1: Press “2nd” and then press “VARS”.This will take you to a DISTR screen.

Step 2: Now, select “normalcdf “i.e. 2nd option, and then press “ENTER” to bring up the normalcdf wizard screen.

Step 3: Enter the lower bound, z-score followed by 0 for mean and 1 for standard deviation.

For example, to find the Percentiles for z-score of 1.2,

type -1000,1.2,0,1. Here the lower bound is infinity, so type -1000.

Always use the large numbers to represent infinity, like -1000 in this case.

Step 4: Type a closing parentheses “)” and then press ENTER.

The TI-84 Plus will calculate the percentile associated with the given z-score.

Let’s discuss a few examples to find percentiles from Z-score on TI-84

How to find Percentile of Negative Z-score on TI-84 ?

Let’s consider an example to find percentile from z score -1.58 on TI-84 calculator

The following steps will guide us on how to calculate the Percentiles from Z-Score = -1.58 Using TI-84 Calculator

Let’s draw the normal distribution curve for the given z-score = -1.58

Negative Z score TI-84
Negative Z score

Step 1: Press “2nd” and then press “VARS”.This will take you to a DISTR screen.

Step 2: Select “normalcdf “i.e. 2nd option, and press “ENTER” to bring up the normalcdf wizard screen.

Step 3: Enter the lower bound, z-score followed by 0 for mean and 1 for standard deviation. In this case, type -1000,-1.58,0,1.

Note: Here the lower bound is infinity, so type -1000.

Step 4: Type a closing parentheses “)” and then press ENTER.

The TI-84 Plus will calculate the percentile associated with the given -1.58 z-score.

The resultant percentile for the given z-score = -1.58 is 0.0571

Conclusion: It concludes that 5.71% of the data values in the standard normal distribution lies below the z-score of -1.58.

Cool Tip: How to Calculate Z Score in Excel!

How to find Percentile of Positive Z-score on TI-84 ?

Let’s consider an example to find percentile from z score 0.31 on the TI-84 calculator.

The following steps will guide on how to calculate the Percentiles from Z-Score = 0.31 on TI-84 Calculator:

Step 1: Press “2nd” and then press “VARS”.This will take you to a DISTR screen.

Step 2: Select “normalcdf “i.e. 2nd option, and then press “ENTER” to bring up the normalcdf wizard screen.

Step 3: Enter the lower bound, z-score followed by 0 for mean and 1 for standard deviation. In this case, type -1000,0.31,0,1.

Note: Here the lower bound is infinity, so type -1000.

Step 4: Type a closing parentheses “)” and then press ENTER.

The TI-84 Plus will calculate the percentile associated with the given 0.31 z-score.

The resultant percentile for the given z-score = 0.31 is 0.6217

Conclusion: It concludes that 62.17% of the data values in the standard normal distribution lies below the z-score of 0.31.

Cool Tip: Read more here about how to use a z-score calculator!

Conclusion

I hope the above article to find percentile from z score on the TI-84 calculator is useful to you.

In the above article, we have learned how to find percentile from negative z score on a TI-84 calculator and find percentile from positive z score on the TI-84 calculator.

Normal Cumulative Distribution function normalcdf() function is used to find percentile for given z score on the TI-84 calculator.

Cool Tip: Read more about how to find z score from percentile on Ti-84 plus calculator!

You can find more topics about Z-Score and how to calculate z score given the area on the ZScoreGeek home page.

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