Changes

Since the trees below must have their tap root in the water table, the depth of a water-table can be found by knowing the depth of the tree’s tap root. A rule of thumb states that the tap root of a tree has a depth equal to about 3⁄4 of the height of the tree. The height of a tree can be found by measuring the length of the shadow the tree is casting on the ground and comparing it with the length of the shadow of a stick 100 centimeters long.

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