Atree casts a shadow of 28 feet. at the same time, a biologist who is 7 feet tall casts a shadow of 2 feet.

how tall is the tree?

a.8 feet.
b.14 feet.
c.78 feet.
d.98 feet.

Assuming that this happened at the same environment like the time of day, then we can use ratio and proportion. We relate the height of the tree with its shadow by using the ratio of the biologist's height to his shadow.

Height of tree/Height of its Shadow = Height of biologist/Height of his Shadow
Height of tree/28 = 7/2
Height of tree = 7*28/2
Height of tree = 98 feet

The answer is D.