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5. INDIRECT MEASUREMENT A lighthouse casts a 128-foot shadow. A nearby lamppost that

measures 5.25 feet casts an 8-foot shadow.

Write a proportion that can be used to determine the height of the lighthouse. What is the height of the lighthouse?

MGSE9-12.G.SRT 5

b. 5.25

a. 1285.25; 195 ft

X 128

8 ; 84 ft

128

c. 5.25" 8 ; 672 ft

X 128

d. 3 5.25; 195 ft

Answer :

Using proportions, it is found that the height of the lighthouse is of 84 ft.

  • This question is solved by proportions, using a rule of three.
  • For a height of 5.25 feet, the shadow is of 8 feet. What is the height when the shadow is of 128 feet?

The rule of three is:

5.25 feet - 8 feet

x feet - 128 feet

Applying cross multiplication:

[tex]8x = 5.25(128)[/tex]

[tex]x = \frac{5.25(128)}{8}[/tex]

[tex]x = 84[/tex]

The height of the lighthouse is of 84 ft.

A similar problem, which also uses proportions, is given at https://brainly.com/question/24372153

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