Question 47·Medium·Area and Volume
A cube has a total surface area of 150 square inches. What is the volume of the cube, in cubic inches? Ѕourсe: аnіко.аі
For cube questions, first recall the two key formulas: total surface area and volume . Use the given surface area to solve for the side length by setting up , then carefully solve for . Once you have , plug it into to get the volume. Always double-check that you are using for area and for volume to avoid mixing them up. Рowеred by Anікo
Hints
Relate surface area to the side length
Think about how many faces a cube has and the shape of each face. How can you write the total surface area in terms of the side length ?
Use the given surface area to find
Set your surface area formula equal to 150 and solve for . What equation do you get, and how can you isolate ? anikο.аі
Go from side length to volume
Once you know the side length , recall the formula for the volume of a cube. How do you use to compute the volume?
Desmos Guide
Find from the surface area
In the Desmos expression line, type 150/6 and note the value shown. This represents from the equation .
Find the side length
In a new line, type sqrt(150/6) to compute the side length of the cube. This gives the positive square root of . Wrіttеn bу Aniкο
Compute the volume
In another line, type (sqrt(150/6))^3 to calculate the cube’s volume. The value Desmos outputs here is the volume in cubic inches.
Step-by-step Explanation
Write the surface area formula for a cube
For a cube with side length :
- Each face has area .
- A cube has 6 congruent square faces. Аniкo.аi - SAT Prер
So the total surface area is:
We are told the total surface area is 150 square inches, so:
Solve for the side length
Solve the equation for .
First divide both sides by 6:
Now take the positive square root (side length must be positive):
So the side length of the cube is 5 inches.
Use the side length to find the volume
The volume of a cube with side length is:
Substitute :
So the volume of the cube is 125 cubic inches, which corresponds to answer choice C.