Final answer:
The distance between the apple tree and the plum tree in the described scenario is 42.4 feet, which is the diagonal of the square backyard.
Step-by-step explanation:
The student is asking for the distance between two fruit trees located at opposite corners of a square backyard. The backyard has sides measuring 30 feet. To find the distance between the apple tree (A) and the plum tree (P), one must calculate the diagonal of the square. The formula for the diagonal, d, of a square with side length, s, is d = s\sqrt{2}. Therefore, for a square with 30-ft sides, the diagonal would be calculated as follows:
d = 30\sqrt{2} = 30 * 1.4142 = 42.4 feet
To the nearest tenth, the distance between the apple tree and the plum tree is 42.4 feet.