This app allows you to compare the batting averages for two players.[br][list][*]Player 1 got m hits in 10 at-bats during the first half of a baseball game and n hits in 20 at-bats during the second half.[/*][*]Player 2 got p hits in 21 at-bats during the first half and q hits in 9 at-bats during the second half.[/*][/list][br]The area models below compare the batting averages of the two players during:[list][*]the first half and second half of the game (shown as side-by-side rectangles for each player), and[br][/*][*]the entire game.[/*][/list][br]In each area model:[list][*]the [b]height[/b] of a rectangle represents the batting average,[/*][*]the [b]width[/b] represents the number of at-bats, and[/*][*]the [b]area[/b] represents the number of hits.[/*][/list]

1. How many cm is the length if the width is 21 cm?[br]2. How are the two quantities [i]x[/i] and [i]y[/i] related?[br]3. What is invariant? (a) sum of the two quantities [i]x[/i] + [i]y[/i], (b) difference between the two quantities [i]x[/i] - [i]y[/i], (c) product of the two quantities [i]xy[/i], or (d) ratio of the two quantities [i]y[/i]/[i]x[/i]? Why?