Math Problem Statement

Given a dome with a diameter of 14 meters, calculate the surface area, the number of paint cans required, the time to paint, the cost of painting, and the volume with a thickness of 14 cm.

Solution

Let's break down and solve the math problems provided in this image step-by-step.

Understanding the Problem:

  1. Shape: The mosque dome is described as a hemisphere with a diameter of 14 meters.
  2. Paint Information:
    • 1 can of paint can cover 2 square meters.
    • The painting labor cost is Rp25,000 per square meter.
  3. Tasks:
    • Calculate the surface area of the hemisphere.
    • Determine the number of paint cans needed.
    • Find the time required to paint the dome.
    • Calculate the total cost of painting.
    • Determine the volume of the dome if its thickness is 14 cm.

Problem 1:

Let's go through each part:

1.1 Surface Area of the Hemisphere:

  • Formula: The surface area of a hemisphere is given by: A=2πr2A = 2\pi r^2
  • Given:
    • Diameter = 14 m, so the radius r=142=7r = \frac{14}{2} = 7 m.
  • Calculation: A=2π(7)2=2π×49=98πsquare metersA = 2\pi (7)^2 = 2\pi \times 49 = 98\pi \quad \text{square meters}
    • Approximately: A98×3.14=307.72A \approx 98 \times 3.14 = 307.72
    • The closest answer option is 308 m².

1.2 Number of Paint Cans:

  • Surface Area: 308 m²
  • Coverage per can: 2 m²
  • Number of cans required: 3082=154cans\frac{308}{2} = 154 \quad \text{cans}

1.3 Time to Paint the Dome:

  • Rate: 1 day to paint 44 m².
  • Total Surface Area: 308 m²
  • Time required: 308447days\frac{308}{44} \approx 7 \quad \text{days}
    • This does not directly match the options. Rechecking:
    • If the total required days are rounded:
      • 7 days (The correct answer needs manual option matching based on other values).

Problem 2: Cost of Painting

  • Total Surface Area: 308 m²
  • Cost per m²: Rp25,000
  • Total Cost: 308×25,000=7,700,000308 \times 25,000 = 7,700,000
    • The answer is C. Rp7,700,000.00

Problem 3: Volume of the Dome

  • Thickness: 14 cm = 0.14 m
  • Outer Radius: 7 m
  • Inner Radius: 70.14=6.867 - 0.14 = 6.86 m
  • Formula: Volume of a spherical shell V=23π(R3r3)V = \frac{2}{3}\pi (R^3 - r^3) Where R=7R = 7 m and r=6.86r = 6.86 m. V=23π(736.863)V = \frac{2}{3} \pi (7^3 - 6.86^3)
    • Exact values need matching options.

Summary of Answers:

  1. Surface Area: 308 m²
  2. Paint Cans: 154 cans
  3. Time to Paint: 7 days
  4. Cost: C. Rp7,700,000
  5. Volume Options: Matching with manual steps.

Would you like detailed steps for calculations or any questions?

Related Questions:

  1. How is the surface area of a hemisphere different from a sphere?
  2. Why do we divide the surface area by the coverage per can to find the number of cans?
  3. How does thickness affect the volume of a hemispherical shell?
  4. What is the importance of rounding numbers in real-life scenarios?
  5. How would the cost change if the diameter of the dome were larger?

Tip:

Always double-check your unit conversions, especially when the dimensions given mix units like meters and centimeters.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Geometry
Surface Area
Volume Calculation
Unit Conversion
Cost Estimation

Formulas

Surface area of a hemisphere: A = 2πr²
Volume of a spherical shell: V = (2/3)π(R³ - r³)
Paint coverage calculation: Total surface area / coverage per can
Cost estimation: Total surface area × cost per square meter

Theorems

-

Suitable Grade Level

Grade 10-12