Question

A simplified model of a particular monument is a rectangular pyramid placed on top of a rectangular prism, as shown. The volume of the monument is 66 cubic feet. Determine whether the given measurement could be the height of the monument.
Select Yes or No for A-C.

A. 10 feet

Yes No


B. 13 feet

Yes No


C. 15 feet

Yes No

Answer 1

*See attachment for the simplified model of the monument

Answer:

The correct option is B. 13ft.

YES to option B. NO to A and C.

Step-by-step Explanation:

=>Given: Model of the monument consisting of a rectangular pyramid and a rectangular prism having a total volume of 66ft³.

Volume of monument = Volume of Pyramid + Volume of Prism = 66ft³

=>Dimensions of given rectangular pyramid:

base length (l) = 3ft

base width = 2ft

height of pyramid (h) = ? (h = Unknown)

Base Area (B) = l × w = 3 × 2 = 6ft²

Volume of pyramid = ⅓ × base area (B) × h = ⅓ × 6 × h

V of Pyramid = 2h ft³

=> Dimensions of the rectangular prism:

base length (l) = 3ft

base width (w) = 2ft

Height of prism (h) = 10ft

Base area (B) = l × w = 3 × 2 = 6 ft³

Volume of prism = base area (B) × height (h)

V of prism = 6 × 10 = 60 ft³

We are required to find the possible height of the monument.

Height of monument = height of pyramid + height of prism

Height of pyramid is unknown (h)

Height of prism = 10ft

Let's find the height of the pyramid using the Volume of the monument = volume of pyramid + volume of prism

Thus,

V of monument = 66 ft³

V of pyramid = 2h ft³

V of prism = 60 ft³

Therefore,

66 = 2h + 60

Subtract 60 from both sides

66 - 60 = 2h + 60 - 60

6 = 2h

Divide both sides by 2

3 = h

Height of pyramid (h) = 3ft

Height of monument = h of Pyramid + h of prism

Height of monument = 3 + 10

Height of monument = 13ft.

The correct option is B. 13ft.

YES to option B. NO to A and C.