Calculate Cuboid Volume: Surface Area 136 cm³ with 8 cm Length Problem

Surface Area Formula with Missing Dimensions

Given the surface area of the cuboid equal to 136 cm3

Length of the cuboid is equal to 8 cm and the width is equal to half the length.

Calculate the volume of the cube

888

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:12 Let's calculate the volume of the box.
00:15 First, set the length according to the data. Then, solve for the width.
00:25 Great! This is the width of the box.
00:29 Next, we use the formula to calculate the surface area.
00:38 It's 2 times the sum of the face areas.
00:45 Now, insert the values and solve for the height of the box.
01:05 Simply divide by 2.
01:16 Then, isolate H, the height.
01:36 And there you have it, the height of the box.
01:40 Now, let's calculate the box volume.
01:51 Multiply width, height, and length together.
01:55 Insert the values and solve.
02:13 And that's how we find the solution. Well done!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Given the surface area of the cuboid equal to 136 cm3

Length of the cuboid is equal to 8 cm and the width is equal to half the length.

Calculate the volume of the cube

888

2

Step-by-step solution

To solve this problem, follow these steps:

  • Step 1: Identify the given information: l=8cm l = 8 \, \text{cm} , w=4cm w = 4 \, \text{cm} , and S=136cm2 S = 136 \, \text{cm}^2 .
  • Step 2: Use the surface area formula to find height h h : 136=2(84+8h+4h) 136 = 2(8 \cdot 4 + 8 \cdot h + 4 \cdot h) .
  • Step 3: Simplify and solve for h h .
  • Step 4: Use the volume formula V=lwh V = l \cdot w \cdot h .
  • Step 5: Substitute the value of h h into the volume formula.
  • Step 6: Calculate and obtain the final result.

Now, let's calculate:

Starting with the surface area equation:

136=2(84+8h+4h) 136 = 2(8 \cdot 4 + 8 \cdot h + 4 \cdot h) .

Simplifying gives:

136=2(32+8h+4h) 136 = 2(32 + 8h + 4h) .

136=2(32+12h) 136 = 2(32 + 12h) .

136=64+24h 136 = 64 + 24h .

Subtract 64 from both sides:

72=24h 72 = 24h .

Divide both sides by 24:

h=3cm h = 3 \, \text{cm} .

Now, calculate the volume using V=lwh V = l \cdot w \cdot h :

V=843 V = 8 \cdot 4 \cdot 3 .

V=96cm3 V = 96 \, \text{cm}^3 .

Therefore, the volume of the cuboid is 96cm3 96 \, \text{cm}^3 .

3

Final Answer

96 cm³

Key Points to Remember

Essential concepts to master this topic
  • Formula: Surface area of cuboid = 2(lw + lh + wh)
  • Method: Find unknown height using 136 = 2(32 + 12h), solve h = 3
  • Check: Volume = 8 × 4 × 3 = 96 cm³ matches surface area ✓

Common Mistakes

Avoid these frequent errors
  • Confusing surface area with volume units
    Don't use cm³ for surface area = wrong formula application! Surface area measures flat covering space (cm²), while volume measures internal space (cm³). Always use surface area formula SA = 2(lw + lh + wh) to find missing dimensions first.

Practice Quiz

Test your knowledge with interactive questions

A rectangular prism has a base measuring 5 units by 8 units.

The height of the prism is 12 units.

Calculate its volume.

121212888555

FAQ

Everything you need to know about this question

Why is the surface area given in cm³ when it should be cm²?

+

Good catch! This appears to be a typo in the problem. Surface area should always be in square units (cm²). The calculation still works the same way using SA=2(lw+lh+wh) SA = 2(lw + lh + wh) .

How do I find the width if it's half the length?

+

Since length = 8 cm, and width = half the length, then width = 82=4 \frac{8}{2} = 4 cm. Always calculate known dimensions first!

What's the difference between finding height from surface area vs. volume?

+

With surface area, you use SA=2(lw+lh+wh) SA = 2(lw + lh + wh) to find the missing dimension. With volume, you'd use V=l×w×h V = l \times w \times h . Surface area considers all 6 faces!

How do I solve 136 = 2(32 + 12h) step by step?

+

Step 1: Divide both sides by 2: 68=32+12h 68 = 32 + 12h

Step 2: Subtract 32: 36=12h 36 = 12h

Step 3: Divide by 12: h=3 h = 3 cm

Why do we multiply by 2 in the surface area formula?

+

A cuboid has 6 faces that come in 3 pairs of identical rectangles! The formula 2(lw+lh+wh) 2(lw + lh + wh) accounts for both faces of each pair: 2 top/bottom + 2 front/back + 2 left/right.

🌟 Unlock Your Math Potential

Get unlimited access to all 18 Cuboids questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations