AP Statistics Using and Finding Students t Finding

Finding Critical Values using a Calculator • Find the DISTR (2 nd VARS) •

Finding Probabilities using a Calculator • Find the DISTR (2 nd VARS) • Remember

Using t tables and your calculator, estimate: • the critical value of t for

Using t tables and your calculator, estimate: • the P-value for t≥ 2. 09

Using t tables and your calculator, estimate: • the P-value for the absolute value

Using t tables and your calculator, estimate: • the P-value for t≤ 2. 19

• Describe how the shape, center, and spread of t-models change as the

• Describe how the critical value of t for a 95% confidence interval

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AP Statistics Using and Finding “Student’s t”

Finding Critical Values using a Calculator • Find the DISTR (2 nd VARS) • Remember inv. Norm? Well, now look for inv. T ** If you have a TI-83 then you need to come see me. You do not have this on yours • You will need to specify the percentile you are looking for AND the df ▫ For example: if we have 6 degrees of freedom and we want to make a 95% CI ◦ inv. T(. 975, 6) will be what we enter

Finding Probabilities using a Calculator • Find the DISTR (2 nd VARS) • Remember normalcdf? We are now looking for tcdf • Let’s use a t of 1. 645 with 12 degrees of freedom • Enter (1. 645, 99, 12) • What do you get? ▫ Did you get 0. 0629457739?

Using t tables and your calculator, estimate: • the critical value of t for a 90% confidence interval with df=17 • The Critical value is 1. 740 Do you get 0. 049964616573?

Using t tables and your calculator, estimate: • the critical value of t for a 98% confidence interval with df=88 • The Critical value is 2. 37 Did you get 0. 009986616053

Using t tables and your calculator, estimate: • the P-value for t≥ 2. 09 with 4 degrees of freedom • The P-value is. 052415327

Using t tables and your calculator, estimate: • the P-value for the absolute value of t is greater than 1. 78 with 22 degrees of freedom • The P-value is. 0888939071

Using t tables and your calculator, estimate: • the critical value of t for a 95% confidence interval with df=7 • The critical value is 2. 36

Using t tables and your calculator, estimate: • the critical value of t for a 99% confidence interval with df=102 • The critical value is 2. 62

Using t tables and your calculator, estimate: • the P-value for t≤ 2. 19 with 41 degrees of freedom • The P-value is. 9828655678

Using t tables and your calculator, estimate: • the P-value for the absolute value of t is greater than 2. 33 with 12 degrees of freedom • The P-value is. 0380704181

• Describe how the shape, center, and spread of t-models change as the number of degrees of freedom increases. The shape becomes closer to Normal, the center does not change, and the spread becomes narrower.

• Describe how the critical value of t for a 95% confidence interval changes as the number of degrees of freedom increases. The Critical value becomes smaller, approaching 1. 96