ISEE Upper Level Quantitative : Geometry

Study concepts, example questions & explanations for ISEE Upper Level Quantitative

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Example Questions

Example Question #1 : How To Find The Length Of An Edge

A cube has sidelength one and one-half feet; a rectangular prism of equal volume has length 27 inches and height 9 inches. Give the width of the prism in inches.

Possible Answers:

Correct answer:

Explanation:

One and one half feet is equal to eighteen inches, so the volume of the cube, in cubic inches, is the cube of this, or

 cubic inches.

The volume of a rectangular prism is

Since its volume is the same as that of the cube, and its length and height are 27 and 9 inches, respectively,  we can rewrite this as

The width is 24 inches.

Example Question #2 : Solid Geometry

A cube has sidelength one and one-half feet; a rectangular prism of equal surface area has length 27 inches and height 9 inches. Give the width of the prism in inches.

Possible Answers:

Correct answer:

Explanation:

One and one half feet is equal to eighteen inches, so the surface area of the cube, in square inches, is six times the square of this, or

 square inches.

The surface area of a rectangular prism is determined by the formula

.

So, with substitutiton, we can find the width:

 inches

 

Example Question #2 : Solid Geometry

A rectangular prism has volume one cubic foot; its length and width are, respectively, 9 inches and  inches. Which of the following represents the height of the prism in inches?

Possible Answers:

Correct answer:

Explanation:

The volume of a rectangular prism is the product of its length, its width, and its height. The prism's volume of one cubic foot is equal to  cubic inches.

Therefore,  can be rewritten as .

We can solve for  as follows:

Example Question #1 : Find The Volume Of A Right Rectangular Prism With Fractional Edge Lengths: Ccss.Math.Content.6.G.A.2

A large crate in the shape of a rectangular prism has dimensions 5 feet by 4 feet by 12 feet. Give its volume in cubic yards.

Possible Answers:

Correct answer:

Explanation:

Divide each dimension by 3 to convert feet to yards, then multiply the three dimensions together:

Example Question #1 : Prisms

Which is the greater quantity?

(A) The volume of a rectangular solid ten inches by twenty inches by fifteen inches

(B) The volume of a cube with sidelength sixteen inches

Possible Answers:

It is impossible to determine which is greater from the information given

(A) is greater 

(A) and (B) are equal

(B) is greater 

Correct answer:

(B) is greater 

Explanation:

The volume of a rectangular solid ten inches by twenty inches by fifteen inches is 

 cubic inches.

The volume of a cube with sidelength 13 inches is 

 cubic inches.

This makes (B) greater

Example Question #301 : Isee Upper Level (Grades 9 12) Quantitative Reasoning

Pyramid 1 has a square base with sidelength ; its height is .

Pyramid 2 has a square base with sidelength ; its height is .

Which is the greater quantity?

(a) The volume of Pyramid 1

(b) The volume of Pyramid 2

 

Possible Answers:

(a) is greater.

(a) and (b) are equal.

It is impossible to tell from the information given.

(b) is greater.

Correct answer:

(b) is greater.

Explanation:

Use the formula on each pyramid.

(a) 

(b) 

Regardless of , (b) is the greater quantity.

Example Question #1 : How To Find The Volume Of A Pyramid

Which is the greater quantity?

(a) The volume of a pyramid with height 4, the base of which has sidelength 1

(b) The volume of a pyramid with height 1, the base of which has sidelength 2

Possible Answers:

It is impossible to tell from the information given.

(a) is greater.

(a) and (b) are equal.

(b) is greater.

Correct answer:

(a) and (b) are equal.

Explanation:

The volume of a pyramid with height  and a square base with sidelength  is 

.

(a) Substitute 

(b) Substitute 

The two pyramids have equal volume.

Example Question #1 : Solid Geometry

Which is the greater quantity? 

(a) The volume of a pyramid whose base is a square with sidelength 8 inches

(b) The volume of a pyramid whose base is an equilateral triangle with sidelength one foot

Possible Answers:

(a) is greater.

It is impossible to tell from the information given.

(a) and (b) are equal.

(b) is greater.

Correct answer:

It is impossible to tell from the information given.

Explanation:

The volume of a pyramid is one-third of the product of the height and the area of the base. The areas of the bases can be calculated, but no information is given about the heights of the pyramids. There is not enough information to determine which one has the greater volume.

Example Question #2 : How To Find The Volume Of A Pyramid

A pyramid with a square base has height equal to the perimeter of its base. Its volume is . In terms of , what is the length of each side of its base?

Possible Answers:

Correct answer:

Explanation:

The volume of a pyramid is given by the formula

where  is the area of its base and  is its height.

Let  be the length of one side of the square base. Then the height is equal to the perimeter of that square, so

and the area of the base is 

So the volume formula becomes

Solve for :

Example Question #4 : Pyramids

A pyramid with a square base has height equal to the perimeter of its base. Which is the greater quantity?

(A) Twice the area of its base

(B) The area of one of its triangular faces

Possible Answers:

(A) and (B) are equal

(B) is greater

It is impossible to determine which is greater from the information given

(A) is greater

Correct answer:

(B) is greater

Explanation:

Since the answer is not dependent on the actual dimensions, for the sake of simplicity, we assume that the base has sidelength 2. Then the area of the base is the square of this, or 4.

The height of the pyramid is equal to the perimeter of the base, or . A right triangle can be formed with the lengths of its legs equal to the height of the pyramid, or 8, and one half the length of a side, or 1; the length of its hypotenuse, which is the slant height, is 

This is the height of one triangular face; its base is a side of the square, so the length of the base is 2. The area of a face is half the product of these dimensions, or 

Since twice the area of the base is , the problem comes down to comparing  and ; the latter, which is (B), is greater.

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