All ISEE Upper Level Quantitative Resources
Example Questions
Example Question #1 : How To Find The Radius Of A Sphere
The volume of a sphere is one cubic yard. Give its radius in inches.
The volume of a sphere with radius is
.
To find the radius in yards, we set and solve for .
yards.
Since the problem requests the radius in inches, multiply by 36:
Example Question #1 : Spheres
In terms of , give the volume, in cubic feet, of a spherical tank with diameter 36 inches.
36 inches = feet, the diameter of the tank. Half of this, or feet, is the radius. Set , substitute in the volume formula, and solve for :
Example Question #2 : Spheres
Which is the greater quantity?
(a) The volume of a sphere with radius
(b) The volume of a cube with sidelength
It is impossible to tell from the information given
(a) is greater
(b) is greater
(a) and (b) are equal
(b) is greater
A sphere with radius has diameter and can be inscribed inside a cube of sidelength . Therefore, the cube in (b) has the greater volume.
Example Question #3 : Spheres
Which is the greater quantity?
(a) The volume of a cube with sidelength inches.
(b) The volume of a sphere with radius inches.
It is impossible to tell from the information given.
(a) and (b) are equal.
(a) is greater.
(b) is greater.
(a) is greater.
You do not need to calculate the volumes of the figures. All you need to do is observe that a sphere with radius inches has diameter inches, and can therefore be inscribed inside the cube with sidelength inches. This give the cube larger volume, making (a) the greater quantity.
Example Question #3 : Spheres
Which is the greater quantity?
(a) The volume of a sphere with diameter one foot
(b)
(a) and (b) are equal.
(b) is greater.
(a) is greater.
It is impossible to tell from the information given.
(a) is greater.
The radius of the sphere is one half of its diameter of one foot, which is six inches, so substitute :
cubic inches,
which is greater than .
Example Question #5 : Spheres
is a positive number. Which is the greater quantity?
(A) The volume of a cube with edges of length
(B) The volume of a sphere with radius
(A) and (B) are equal
It is impossible to determine which is greater from the information given
(A) is greater
(B) is greater
(A) is greater
No calculation is really needed here, as a sphere with radius - and, subsequently, diameter - can be inscribed inside a cube of sidelength . This makes (A), the volume of the cube, the greater.
Example Question #6 : Spheres
Which is the greater quantity?
(a) The radius of a sphere with surface area
(b) The radius of a sphere with volume
It cannot be determined which of (a) and (b) is greater
(a) is the greater quantity
(a) and (b) are equal
(b) is the greater quantity
(a) and (b) are equal
The formula for the surface area of a sphere, given its radius , is
The sphere in (a) has surface area , so
The formula for the volume of a sphere, given its radius , is
The sphere in (b) has volume , so
The radius of both spheres is 3.
Example Question #6 : Spheres
In terms of , give the surface area, in square inches, of a spherical water tank with a diameter of 20 feet.
feet = inches, the diameter of the tank; half of this, or 120 inches, is the radius. Set , substitute in the surface area formula, and solve for :
Example Question #1 : How To Find The Surface Area Of A Sphere
Which is the greater quantity?
(a) The surface area of a sphere with radius 1
(b) 12
(a) is greater.
(b) is greater.
(a) and (b) are equal.
It is impossible to tell from the information given.
(a) is greater.
The surface area of a sphere can be found using the formula
.
The surface area of the given sphere can be found by substituting :
so , or
This makes (a) greater.
Example Question #5 : Spheres
Sphere A has volume . Sphere B has surface area . Which is the greater quantity?
(a) The radius of Sphere A
(b) The radius of Sphere B
(a) and (b) are equal
(a) is greater
(b) is greater
It is impossible to tell from the information given
(b) is greater
(a) Substitute in the formula for the volume of a sphere:
inches
(b) Substitute in the formula for the surface area of a sphere:
inches
(b) is greater.