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How to find a normal distribution probability on a TI-84 Plus CE or TI-84 Plus

By E-Code · updated

Press 2nd DISTR (above VARS) and 2 for normalcdf(. In the wizard type lower, upper, μ and σ, pressing ENTER after each, then ENTER on Paste and ENTER again: normalcdf(-1,1,0,1) 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. A wizard opens.
  3. Lower: −1. (-) 1 ENTER Type (−) 1 and ENTER: start one standard deviation below the mean. Use the (−) key, not minus.
  4. Upper: 1. 1 ENTER Type 1 and ENTER: end one standard deviation above.
  5. Keep μ = 0 and σ = 1. ENTER ENTER Press ENTER twice: mean 0 and standard deviation 1, the standard normal curve. For real data, type its mean and SD here.
  6. Paste. ENTER The cursor is on Paste. Press ENTER: the command goes to the home screen.
  7. Work it out. ENTER Press ENTER.
  8. Read the area. .6827: about 68% of a normal curve lies within one standard deviation of the mean.

What the screen shows

.6827: about 68% of a normal curve lies within one standard deviation of the mean.

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

Related

Statistics programs for the TI-84 Plus CE:

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