2.72 Compare the predictions. Refer to the two previous exercises. You have predicted two dominant-arm bone strengths, one for a baseball player and one for a person who is not a baseball player. The nondominant bone strengths are both 16.0 cm⁴/1000.

1. (a) Compare the two predictions by computing the difference in means, baseball player minus control.

2. (b) Explain how the difference in the two predictions is an estimate of the effect of baseball throwing exercise on the strength of arm bones.

3. (c) For nondominant arm strengths of 12 cm⁴/1000 and 20 cm⁴/1000, repeat your predictions and take the differences. Make a table of the results of all three calculations (for 12, 16, and 20 cm⁴/1000).

4. (d) Write a short summary of the results of your calculations for the three different nondominant-arm strengths. Be sure to include an explanation of why the differences are not the same for the three nondominant-arm strengths.