Chapter 12, number 1a in our fast track book asks us to find a 97% confidence interval for the true population slope. To do so, we must understand both our formula for confidence intervals and the computer printout.
Formula
b - t (E) < B < b + t(E)
where b is our given slope value from the printout. (Coefficient for Registrations) = 9.2472
E is our standard error of the coefficient for the slope. (SE coef for Registrations) = .2145
and "t" is our t-score.
Since B is the parameter we are trying to estimate, it would not make sense to use it in our formula to find "t". Therefore "t" is taken straight from our student's t-distribution chart. The degrees of freedom is seven and we look across for 97%. However, we see there is only a value given for 95% and 98% in our Actual textbook. The value at 95% IS 2.365 and the value at 98% is 2.998. Therefore 97% falls somewhere in between. A good estimate of this can be made around 2.75 however, the Fast Track book reveals its exact answer to be 2.715.
So, since
b - t (E) < B < b + t(E)
9.2472 - 2.715 (.2145) < B < 9.2472 + 2.715 (.2145)
Since we likely would use an estimate of "t" and not the exact value in this case, 2.7 or 2.75 would have sufficed. However, I believe it likely that on the AP exam, they will give a value that is easily obtained from the chart or easily estimated.
Any more questions on this can be answered tomorrow.
Tuesday, May 10, 2016
Sunday, May 8, 2016
Week of May 9th
Geometry: Continue with circles. This will include a possible retest from last week so study up!
Algebra 1: Students will continue to factor polynomials.
Stats: Students will conduct their hypothesis test on a speed trap for the proportion of people who speed through the school zone.
AP Stats: Review for AP test! Test is on Thursday!
Algebra 1: Students will continue to factor polynomials.
Stats: Students will conduct their hypothesis test on a speed trap for the proportion of people who speed through the school zone.
AP Stats: Review for AP test! Test is on Thursday!
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