In-class students provided estimates of the angles x and y in the ladder handout; their estimates for x were: 45, 45, 45, 45, 45, 47, 50, 50, 50, and their estimates for y were: 65, 67, 70, 70, 70, 70, 70, 75, 77. Enter these values in a Minitab worksheet in C1 and C2, and label the columns, respectively, "Angle x" and "Angle y".
Then label C3 "Height for x" and C4, "Height for y". To compute C3, select Calc>Calculator..., enter C3 in the "Store result in variables:" box, and then enter 30*sin(radians(C1)) in the Expression box. Repeat the procedure for C4, making the necessary substitutions.
Then construct side-by-side histograms of C1 and C2 to confirm that the students' angle estimates have approximately the same precision. In practice, the estimate of x usually has more precision, since x is close to a 45 degree angle, and students' estimates cluster around that value. To generate the histograms, select Graph>Histogram..., then select OK under the Simple box, then select Angle x and Angle y in the "Graph variables:" box. Select Multiple Graphs..., then select "In separate panels of the same graph", then "Same Y", then "Same X, including same bins". The resulting histograms have few bins, but they show approximately the same variability.
Repeat the exercise with "Height for x" and "Height for y". The estimates of H based on estimating y should be more precise. Since H is unknown, we have no method for assessing accuracy.