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How to find a confidence interval for a mean on a TI-84 Plus CE, TI-84 Plus or TI-83 Plus

By E-Code · updated

Press STAT, ▶ twice to TESTS and 8 for TInterval. Pick Stats (▶, ENTER), ▼ and type x̄, Sx, n and the C-Level with ENTER after each, then ENTER on Calculate: x̄ 20, Sx 4, n 16 at .95 gives (17.87, 22.13).

Step by step

  1. Open STAT. STAT Press STAT.
  2. The TESTS tab. ▶ ▶ Press ▶ twice to TESTS: the tests and confidence intervals.
  3. Pick TInterval. 8 Press 8 for TInterval: a range that likely holds the true mean.
  4. Move to Stats. ▶ Press ▶ onto Stats: you'll type the sample's summary instead of a list.
  5. Pick Stats. ENTER Press ENTER. The rows change to x̄, Sx and n.
  6. The sample mean x̄. ▼ 2 0 ENTER Press ▼, then type 20 and ENTER: the sample mean.
  7. The sample SD Sx. 4 ENTER Type 4 and ENTER: the sample standard deviation.
  8. The sample size n. 1 6 ENTER Type 16 and ENTER: 16 values in the sample.
  9. Keep C-Level .95. ENTER Press ENTER to keep C-Level .95: 95% confidence.
  10. Calculate. ENTER The cursor is on Calculate. Press ENTER.
  11. Read the interval. (17.87, 22.13): you can be 95% confident the true mean is between 17.87 and 22.13.

What the screen shows

(17.87, 22.13): you can be 95% confident the true mean is between 17.87 and 22.13.

Look for (17.86855045, 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 confidence interval for a mean” on the TI-84 calculator

Related

Statistics programs for the TI-84 Plus CE:

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