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How to find a normal distribution probability on a TI-83 Plus

By E-Code · updated

Press 2nd DISTR (above VARS) and 2 for normalcdf(, then type lower, upper, mean and SD with commas, close the bracket and press ENTER: normalcdf(-1,1) (mean 0, SD 1 when left out) is .6827.

Step by step

  1. Open DISTR. 2nd VARS Press 2nd, then VARS. DISTR (above VARS) has the probability distributions.
  2. Pick normalcdf(. 2 Press 2 for normalcdf(: the area under the normal curve between two values.
  3. From −1 to 1. (-) 1 , 1 ) Type (−) 1 , 1 ): one standard deviation below to one above. Left out, μ is 0 and σ is 1: the standard normal curve.
  4. Work it out. ENTER Press ENTER.
  5. Read the area. .6827: about 68% of a normal curve lies within one standard deviation of the mean. For real data add its mean and SD: normalcdf(lower, upper, μ, σ).

What the screen shows

.6827: about 68% of a normal curve lies within one standard deviation of the mean. For real data add its mean and SD: normalcdf(lower, upper, μ, σ).

Look for .6826 on the screen.

Try it with the keys lit up

This guide is one of E-Code's Learn lessons. Open it on E-Code's TI-84 calculator and each key lights up in turn as you press it.

Try “Find a normal distribution probability” on the TI-84 calculator

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