### All ACT Math Resources

## Example Questions

### Example Question #1 : Solid Geometry

If we have a regular (the triangles are equilateral) triangular prism of volume and the side length of the triangle on either face is , what is the length of the prism? Write your answer in terms of a decimal rounded to the nearest hundredth.

**Possible Answers:**

Not enough information to decide.

**Correct answer:**

The volume of a triangular prism can be simply stated as V = A*L, where A is the area of the triangular face and L is the length. We have the volume already and we need to figure out the area of the triangle from the side length.

The area of a triangle is b*h/2, and we are given the base/side length: 3 in. We also have a formula for the height of an equilateral triangle, . Calculating the area of the triangle we get 2.5981 in^2, so now we just have to plug our numbers into the volume formula.

And that is the final answer.

### Example Question #1 : Solid Geometry

Roberto has a swimming pool that is in the shape of a rectangular prism. His swimming pool is meters wide, meters long, and meters deep. He needs to fill up the pool for summer, and his hose fills at a rate of cubic meters per hour. How many hours will it take for Roberto to fill up the swimming pool?

**Possible Answers:**

**Correct answer:**

First, find the volume of the pool. For a rectangular prism, the formula for the volume is the following:

For the swimming pool,

cubic meters

Now, because the hose only fills up cubic meters per hour, divide the total volume by to find how long it will take for the pool to fill.

It will take the pool hours to fill by hose.

### Example Question #1 : Solid Geometry

Matt baked a rectangular cake for his mom's birthday. The cake was inches long, inches wide, and inches high. If he cuts the cake into pieces that are inches long, inches wide, and inches high, how many pieces of cake can he cut?

**Possible Answers:**

**Correct answer:**

First, find the volume of the cake. For a rectangular prism,

Next, find the volume of each individual slice.

Now, divide the volume of the entire cake by the volume of the slice to get how many pieces of cake Matt can cut.

### Example Question #1 : Other Polyhedrons

If the side lengths of a cube are tripled, what effect will it have on the volume?

**Possible Answers:**

The volume will be times greater.

The volume will be times greater.

The volume will be times greater.

The volume will be times greater.

**Correct answer:**

The volume will be times greater.

Start by taking a cube that is . The volume of this cube is .

Next, triple the sides of this cube so that it becomes . The volume of this cube is .

The volume of the new cube is times greater than the original.

### Example Question #5 : Solid Geometry

A cube has a surface area of . What is its volume?

**Possible Answers:**

**Correct answer:**

First, find the side lengths of the cube.

Recall that the surface area of the cube is given by the following equation:

, where is the length of a side.

Plugging in the surface area given by the equation, we can then find the side length of the cube.

Now, recall that the volume of a cube is given by the following equation:

### Example Question #1 : Solid Geometry

The volume of the right triangular prism is . Find the value of .

**Possible Answers:**

**Correct answer:**

The volume of a right triangular prism is given by the following equation:

Now, for the given question, the height is .

Since the area of the base is a right triangle, we can plug in the given values to find .

### Example Question #7 : Solid Geometry

The tent shown below is in the shape of a triangular prism. What is the volume of this tent in cubic feet?

**Possible Answers:**

**Correct answer:**

The volume of a right triangular prism is given by the following equation:

### Example Question #8 : Solid Geometry

The height of a box is twice its width and half its length. If the volume of the box is , what is the length of the box?

**Possible Answers:**

**Correct answer:**

For a rectangular prism, the formula for the volume is the following:

Now, we know that the height is twice its width. We can rewrite that as:

We also know that the height is half its length. That can be written as:

Now, we can plug in the values of the length, width, and height in terms of height to find the height.

The question wants to find the length of the box. Plug in the value of the height in the earlier equation we wrote earlier to represent the relatioinship between the height and the length.

### Example Question #9 : Solid Geometry

In cubic inches, find the volume of a tetrahedron that has a surface area of .

**Possible Answers:**

**Correct answer:**

First, we will need to find the length of a side of the tetrahedron.

We can use the surface area to find the lengh of a side. Recall that the formula to find the surface of a tetrahedron:

, where is the side length.

Now, recall the formula to find the volume of a tetrahedron:

### Example Question #10 : Solid Geometry

Susan bought a chocolate bar that came in a container shaped like a triangular prism shown below. If the container is completely filled with chocolate, in cubic inches, what volume of chocoate did Susan buy?

**Possible Answers:**

**Correct answer:**

The volume of a right triangular prism is given by the following equation: