Math Problem Statement

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An in-ground pool is 6 m wide, 15 m long, and 2 m deep. The walls and floor of the pool are to be repainted. What is the total surface area to be repainted?

Solution

To solve this problem, we need to find the total surface area of the walls and the floor of the pool that need to be repainted.

Step-by-step Solution:

  1. Dimensions of the Pool:

    • Width (W): 6 m
    • Length (L): 15 m
    • Depth (D): 2 m
  2. Calculate the Floor Area: The floor of the pool is a rectangle with the length and width of the pool.

    Floor Area=Length×Width=15m×6m=90m2\text{Floor Area} = \text{Length} \times \text{Width} = 15 \, \text{m} \times 6 \, \text{m} = 90 \, \text{m}^2

  3. Calculate the Wall Areas: The walls of the pool consist of two longer walls and two shorter walls.

    • Longer Walls: Each longer wall has a length of 15 m and a height of 2 m.

    Area of One Longer Wall=Length×Height=15m×2m=30m2\text{Area of One Longer Wall} = \text{Length} \times \text{Height} = 15 \, \text{m} \times 2 \, \text{m} = 30 \, \text{m}^2

    Since there are two longer walls:

    Total Area of Longer Walls=2×30m2=60m2\text{Total Area of Longer Walls} = 2 \times 30 \, \text{m}^2 = 60 \, \text{m}^2

    • Shorter Walls: Each shorter wall has a width of 6 m and a height of 2 m.

    Area of One Shorter Wall=Width×Height=6m×2m=12m2\text{Area of One Shorter Wall} = \text{Width} \times \text{Height} = 6 \, \text{m} \times 2 \, \text{m} = 12 \, \text{m}^2

    Since there are two shorter walls:

    Total Area of Shorter Walls=2×12m2=24m2\text{Total Area of Shorter Walls} = 2 \times 12 \, \text{m}^2 = 24 \, \text{m}^2

  4. Calculate the Total Surface Area to be Repainted:

    The total surface area to be repainted is the sum of the floor area and the areas of all four walls.

    Total Surface Area=Floor Area+Total Area of Longer Walls+Total Area of Shorter Walls\text{Total Surface Area} = \text{Floor Area} + \text{Total Area of Longer Walls} + \text{Total Area of Shorter Walls}

    Substituting the values:

    Total Surface Area=90m2+60m2+24m2=174m2\text{Total Surface Area} = 90 \, \text{m}^2 + 60 \, \text{m}^2 + 24 \, \text{m}^2 = 174 \, \text{m}^2

Conclusion:

The total surface area that needs to be repainted is 174 m², which corresponds to option (B).

Would you like any further explanation or have any other questions?

Related Questions:

  1. What would the total surface area be if the depth of the pool were 3 m instead of 2 m?
  2. How would you calculate the volume of the pool?
  3. If the repainting cost is $5 per square meter, what would be the total cost for repainting the pool?
  4. How does the surface area change if the pool is circular with the same area?
  5. What is the perimeter of the pool?

Tip:

When working with geometry problems involving surface areas, always break down complex shapes into simpler ones, calculate each part's area, and then sum them up for the total.

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Math Problem Analysis

Mathematical Concepts

Geometry
Surface Area
Rectangular Prisms

Formulas

Floor Area = Length × Width
Wall Area = Length × Height
Total Surface Area = Floor Area + Wall Areas

Theorems

Surface area calculation for rectangular prisms

Suitable Grade Level

Grades 6-8