Math worksheet for calculating the volume of pyramids, cones, and spheres with provided dimensions.
Worksheet titled "Volume of Pyramids, Cones and Spheres" with eight problems showing geometric shapes and dimensions for calculating volume.
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Show Answer Key & Explanations
Step-by-step solution for: 8th Grade Math Worksheets | Free Downloads Available
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Show Answer Key & Explanations
Step-by-step solution for: 8th Grade Math Worksheets | Free Downloads Available
Here are the step-by-step solutions for each problem on the worksheet.
Formulas needed:
* Volume of a Pyramid: $V = \frac{1}{3} \times \text{Base Area} \times \text{Height}$
* Volume of a Cone: $V = \frac{1}{3} \times \pi \times r^2 \times h$
*(Use $\pi \approx 3.14159$)*
---
* Base: Square with side $4\text{ cm}$.
* Height: $9\text{ cm}$.
* Step 1: Find Base Area. $4 \times 4 = 16\text{ cm}^2$.
* Step 2: Calculate Volume. $\frac{1}{3} \times 16 \times 9$.
* Calculation: $16 \times 3 = 48$.
* Answer: $48\text{ cm}^3$
* Base: Rectangle $12\text{ cm}$ by $6\text{ cm}$.
* Height: $15\text{ cm}$.
* Step 1: Find Base Area. $12 \times 6 = 72\text{ cm}^2$.
* Step 2: Calculate Volume. $\frac{1}{3} \times 72 \times 15$.
* Calculation: $\frac{1}{3}$ of $15$ is $5$. So, $72 \times 5 = 360$.
* Answer: $360\text{ cm}^3$
* Base: Rectangle $5\text{ cm}$ by $7\text{ cm}$.
* Height: $20\text{ cm}$.
* Step 1: Find Base Area. $5 \times 7 = 35\text{ cm}^2$.
* Step 2: Calculate Volume. $\frac{1}{3} \times 35 \times 20$.
* Calculation: $35 \times 20 = 700$. Then $700 \div 3 = 233.333...$
* Answer: $233.33\text{ cm}^3$ (rounded to 2 decimal places)
* Part A: The Pyramid
* Base: Square $3\text{ cm}$ by $3\text{ cm}$. Height: $7\text{ cm}$.
* Volume: $\frac{1}{3} \times (3 \times 3) \times 7 = \frac{1}{3} \times 9 \times 7 = 3 \times 7 = 21\text{ cm}^3$.
* Part B: The Cuboid (Box)
* Dimensions: $3\text{ cm} \times 3\text{ cm} \times 2\text{ cm}$.
* Volume: $3 \times 3 \times 2 = 18\text{ cm}^3$.
* Total Volume: $21 + 18 = 39$.
* Answer: $39\text{ cm}^3$
* Radius ($r$): $3\text{ cm}$.
* Height ($h$): $9\text{ cm}$.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 3^2 = 9$.
* $\frac{1}{3} \times 9 = 3$.
* $3 \times 9 = 27$.
* $27 \times \pi \approx 84.823...$
* Answer: $84.82\text{ cm}^3$
* Radius ($r$): $1.5\text{ cm}$.
* Height ($h$): $7\text{ cm}$.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 1.5^2 = 2.25$.
* $2.25 \times 7 = 15.75$.
* $15.75 \div 3 = 5.25$.
* $5.25 \times \pi \approx 16.493...$
* Answer: $16.49\text{ cm}^3$
* Diameter: $20\text{ cm}$, so Radius ($r$) is $10\text{ cm}$.
* Height ($h$): $24\text{ cm}$.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 10^2 = 100$.
* $100 \times 24 = 2400$.
* $2400 \div 3 = 800$.
* $800 \times \pi \approx 2513.274...$
* Answer: $2513.27\text{ cm}^3$
* Diameter: $7.2\text{ mm}$, so Radius ($r$) is $3.6\text{ mm}$.
* Height ($h$): $7.7\text{ mm}$. *(Note: Use the vertical height, not the slant height of 8.5)*.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 3.6^2 = 12.96$.
* $12.96 \times 7.7 = 99.792$.
* $99.792 \div 3 = 33.264$.
* $33.264 \times \pi \approx 104.499...$
* Answer: $104.50\text{ mm}^3$
──────────────────────────────────────
Final Answer:
1) 48 cm³
2) 360 cm³
3) 233.33 cm³
4) 39 cm³
5) 84.82 cm³
6) 16.49 cm³
7) 2513.27 cm³
8) 104.50 mm³
Formulas needed:
* Volume of a Pyramid: $V = \frac{1}{3} \times \text{Base Area} \times \text{Height}$
* Volume of a Cone: $V = \frac{1}{3} \times \pi \times r^2 \times h$
*(Use $\pi \approx 3.14159$)*
---
1) Square-based Pyramid
* Base: Square with side $4\text{ cm}$.
* Height: $9\text{ cm}$.
* Step 1: Find Base Area. $4 \times 4 = 16\text{ cm}^2$.
* Step 2: Calculate Volume. $\frac{1}{3} \times 16 \times 9$.
* Calculation: $16 \times 3 = 48$.
* Answer: $48\text{ cm}^3$
2) Rectangular-based Pyramid
* Base: Rectangle $12\text{ cm}$ by $6\text{ cm}$.
* Height: $15\text{ cm}$.
* Step 1: Find Base Area. $12 \times 6 = 72\text{ cm}^2$.
* Step 2: Calculate Volume. $\frac{1}{3} \times 72 \times 15$.
* Calculation: $\frac{1}{3}$ of $15$ is $5$. So, $72 \times 5 = 360$.
* Answer: $360\text{ cm}^3$
3) Rectangular-based Pyramid
* Base: Rectangle $5\text{ cm}$ by $7\text{ cm}$.
* Height: $20\text{ cm}$.
* Step 1: Find Base Area. $5 \times 7 = 35\text{ cm}^2$.
* Step 2: Calculate Volume. $\frac{1}{3} \times 35 \times 20$.
* Calculation: $35 \times 20 = 700$. Then $700 \div 3 = 233.333...$
* Answer: $233.33\text{ cm}^3$ (rounded to 2 decimal places)
4) Composite Shape (Pyramid on top of a Cuboid)
* Part A: The Pyramid
* Base: Square $3\text{ cm}$ by $3\text{ cm}$. Height: $7\text{ cm}$.
* Volume: $\frac{1}{3} \times (3 \times 3) \times 7 = \frac{1}{3} \times 9 \times 7 = 3 \times 7 = 21\text{ cm}^3$.
* Part B: The Cuboid (Box)
* Dimensions: $3\text{ cm} \times 3\text{ cm} \times 2\text{ cm}$.
* Volume: $3 \times 3 \times 2 = 18\text{ cm}^3$.
* Total Volume: $21 + 18 = 39$.
* Answer: $39\text{ cm}^3$
5) Cone
* Radius ($r$): $3\text{ cm}$.
* Height ($h$): $9\text{ cm}$.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 3^2 = 9$.
* $\frac{1}{3} \times 9 = 3$.
* $3 \times 9 = 27$.
* $27 \times \pi \approx 84.823...$
* Answer: $84.82\text{ cm}^3$
6) Cone
* Radius ($r$): $1.5\text{ cm}$.
* Height ($h$): $7\text{ cm}$.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 1.5^2 = 2.25$.
* $2.25 \times 7 = 15.75$.
* $15.75 \div 3 = 5.25$.
* $5.25 \times \pi \approx 16.493...$
* Answer: $16.49\text{ cm}^3$
7) Cone
* Diameter: $20\text{ cm}$, so Radius ($r$) is $10\text{ cm}$.
* Height ($h$): $24\text{ cm}$.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 10^2 = 100$.
* $100 \times 24 = 2400$.
* $2400 \div 3 = 800$.
* $800 \times \pi \approx 2513.274...$
* Answer: $2513.27\text{ cm}^3$
8) Cone
* Diameter: $7.2\text{ mm}$, so Radius ($r$) is $3.6\text{ mm}$.
* Height ($h$): $7.7\text{ mm}$. *(Note: Use the vertical height, not the slant height of 8.5)*.
* Formula: $V = \frac{1}{3} \pi r^2 h$
* Calculation:
* $r^2 = 3.6^2 = 12.96$.
* $12.96 \times 7.7 = 99.792$.
* $99.792 \div 3 = 33.264$.
* $33.264 \times \pi \approx 104.499...$
* Answer: $104.50\text{ mm}^3$
──────────────────────────────────────
Final Answer:
1) 48 cm³
2) 360 cm³
3) 233.33 cm³
4) 39 cm³
5) 84.82 cm³
6) 16.49 cm³
7) 2513.27 cm³
8) 104.50 mm³
Parent Tip: Review the logic above to help your child master the concept of math problems for 8th graders worksheet.