Answer: Let x be the height of the Ferris wheel. We can set up a proportion to solve for x:
(mailbox height) / (length of mailbox shadow) = (Ferris wheel height) / (length of Ferris wheel shadow)
Substituting the given values, we get:
4.5 / 6 = x / 84
Simplifying the left side, we get:
0.75 = x / 84
Multiplying both sides by 84, we get:
x = 63
Therefore, the height of the Ferris wheel is 63 feet.