Math Problem Statement

Question: A park is circular in shape with a radius of 35 meters. There is a circular flower bed inside the park with a radius of 14 meters. The remaining area of the park is covered with grass. If the cost of planting grass is ₹5 per square meter, calculate the total cost of planting grass in the park.

Solution

To solve this problem, we need to calculate the area of the grass-covered region in the park and then find the cost of planting grass based on the given rate.

Step-by-Step Solution:

  1. Calculate the total area of the park: The park is circular with a radius of 35 meters. The formula for the area of a circle is:

    Apark=πr2A_{\text{park}} = \pi r^2 where r=35r = 35 meters. So,

    Apark=π(35)2=π×12253848.45square metersA_{\text{park}} = \pi (35)^2 = \pi \times 1225 \approx 3848.45 \, \text{square meters}

  2. Calculate the area of the flower bed: The flower bed is also circular with a radius of 14 meters. Using the same formula for the area of a circle:

    Aflower bed=πr2A_{\text{flower bed}} = \pi r^2 where r=14r = 14 meters. So,

    Aflower bed=π(14)2=π×196615.75square metersA_{\text{flower bed}} = \pi (14)^2 = \pi \times 196 \approx 615.75 \, \text{square meters}

  3. Calculate the remaining area covered with grass: The grass-covered area is the total area of the park minus the area of the flower bed:

    Agrass=AparkAflower bedA_{\text{grass}} = A_{\text{park}} - A_{\text{flower bed}}

    Agrass3848.45615.75=3232.7square metersA_{\text{grass}} \approx 3848.45 - 615.75 = 3232.7 \, \text{square meters}

  4. Calculate the cost of planting grass: The cost of planting grass is ₹5 per square meter. So, the total cost is:

    Total cost=Agrass×5\text{Total cost} = A_{\text{grass}} \times 5

    Total cost3232.7×5=16163.5rupees\text{Total cost} \approx 3232.7 \times 5 = 16163.5 \, \text{rupees}

Final Answer:

The total cost of planting grass in the park is approximately ₹16,163.5.

Would you like more details on any step, or do you have any questions?

Here are 5 related questions for further exploration:

  1. What would the cost be if the rate of planting grass was ₹6 per square meter?
  2. How much area would the park cover if the radius was doubled?
  3. If the flower bed were a rectangle instead of a circle, how would the formula change?
  4. What is the percentage of the park's total area covered by grass?
  5. How would the cost change if the flower bed's radius was increased to 20 meters?

Tip: Always subtract the non-covered areas (like flower beds) from the total area to get the remaining covered area.

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Math Problem Analysis

Mathematical Concepts

Geometry
Area Calculation
Cost Estimation

Formulas

Area of a circle: A = πr^2
Cost of planting grass: Total cost = Area covered × Rate per square meter

Theorems

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Suitable Grade Level

Grades 6-8